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Blunt vs sharp uterine expansion at lower segment cesarean section delivery: a systematic review with metaanalysis

Published:November 02, 2012DOI:https://doi.org/10.1016/j.ajog.2012.10.886

      Objective

      Blunt vs sharp expansion of the uterine incision at cesarean delivery has been investigated as a technique primarily to reduce intraoperative blood loss. The objective of this systematic review was to compare the effects of either intervention on maternal outcomes.

      Study Design

      A systematic review with metaanalyses that used the DerSimonian and Laird random effects model was performed. The Cochrane Central Register of Controlled Trials (The Cochrane Library 2012, Issue 4), MEDLINE (1948–Apr 2012), EMBASE (1947–Apr 2012), and the reference lists/citation history of articles were searched. Only randomized controlled trials were included.

      Results

      Four trials (1731 patients) were evaluated. Data from one recently completed trial (535 patients) were not yet available. Metaanalyses revealed a trend towards reduced maternal blood loss with blunt expansion of the uterine incision that was statistically significant when measured by surgeon's estimation of volume lost, but not by comparison of pre- and postoperative hematocrit and hemoglobin levels or a requirement for blood transfusion. There was a trend towards fewer unintended extensions in the blunt group and no difference in the incidence of endometritis.

      Conclusion

      Blunt dissection of the uterine incision at cesarean delivery appears to be superior to sharp dissection in minimizing maternal blood loss. However, this conclusion could change when data from a new unpublished large trial are available.

      Key words

      The global rate of cesarean deliveries is approximately 15%
      • Betran A.P.
      • Merialdi M.
      • Lauer J.A.
      • et al.
      Rates of caesarean section: analysis of global, regional and national estimates.
      ; the rate in some developed countries reaches as high as 1 in 3.
      Australian Institute of Health and Welfare
      Australia's mothers and babies 2009 Perinatal statistics series no. 25. Cat. no. PER 52.
      • Hamilton B.E.
      • Martin J.A.
      • Ventura S.J.
      Births: preliminary data for 2010.
      It generally is accepted that a greater amount of blood loss is likely in an operative, compared with vaginal, delivery. As obstetric hemorrhage remains a leading cause of maternal morbidity and death, techniques such as manual placental extraction, in situ uterine repair in the place of exteriorization, and blunt traction in the cephalocaudad, rather than transverse, direction for uterine incision have been proposed to minimize intraoperative blood loss during cesarean delivery.
      • Anorlu R.I.
      • Maholwana B.
      • Hofmeyr G.J.
      Methods of delivering the placenta at caesarean section.
      • Bolla D.
      • Schöning A.
      • Drack G.
      • Hornung R.
      Technical aspects of the cesarean section.
      • Cromi A.
      • Ghezzi F.
      • Di Naro E.
      • Siesto G.
      • Loverro G.
      • Bolis P.
      Blunt expansion of the low transverse uterine incision at cesarean delivery: a randomized comparison of 2 techniques.
      • Jacobs-Jokhan D.
      • Hofmeyr G.
      Extra-abdominal versus intra-abdominal repair of the uterine incision at caesarean section.
      Blunt expansion of the uterine incision with fingers, rather than scissors, is one other such suggestion.
      • Berghella V.
      • Baxter J.K.
      • Chauhan S.P.
      Evidence-based surgery for cesarean delivery.
      Previously, proponents of either the blunt or sharp method would defer to training protocols, personal experience, or theoretic reasoning to explain their choice of technique. To date, a small number of studies specifically have examined the impact of the hysterotomy expansion technique on maternal blood loss during cesarean delivery. The main suggested advantage of the blunt approach includes decreased trauma to the vasculature with less bleeding and ooze from the dissected myometrial edge.
      • Hidar S.
      • Jerbi M.
      • Hafsa A.
      • Slama A.
      • Bibi M.
      • Khairi H.
      [The effect of uterine incision expansion at caesarean delivery on perioperative haemorrhage: a prospective randomised clinical trial].
      • Magann E.F.
      • Chauhan S.P.
      • Bufkin L.
      • Field K.
      • Roberts W.E.
      • Martin Jr, J.N.
      Intra-operative haemorrhage by blunt versus sharp expansion of the uterine incision at caesarean delivery: a randomised clinical trial.
      • Rodriguez A.I.
      • Porter K.B.
      • O'Brien W.F.
      Blunt versus sharp expansion of the uterine incision in low-segment transverse cesarean section.
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      Secondary potential benefits include less risk of injury to the neonate and cord and increased speed of delivery.
      • Hameed N.
      • Ali M.A.
      Maternal blood loss by expansion of uterine incision at caesarean section: a comparison between sharp and blunt techniques.
      • Smith J.F.
      • Hernandez C.
      • Wax J.R.
      Fetal laceration injury at cesarean delivery.
      • Song S.H.
      • Oh M.J.
      • Kim T.
      • Hur J.Y.
      • Saw H.S.
      • Park Y.K.
      Finger-assisted stretching technique for cesarean section.
      However, there are concerns about reduced control of length and direction of the uterine incision that potentially could cause damage of lateral uterine and parametrial blood vessels and increased risk of unintended extensions that could contribute further to hemorrhage.
      • Cromi A.
      • Ghezzi F.
      • Di Naro E.
      • Siesto G.
      • Loverro G.
      • Bolis P.
      Blunt expansion of the low transverse uterine incision at cesarean delivery: a randomized comparison of 2 techniques.
      • Hidar S.
      • Jerbi M.
      • Hafsa A.
      • Slama A.
      • Bibi M.
      • Khairi H.
      [The effect of uterine incision expansion at caesarean delivery on perioperative haemorrhage: a prospective randomised clinical trial].
      • Magann E.F.
      • Chauhan S.P.
      • Bufkin L.
      • Field K.
      • Roberts W.E.
      • Martin Jr, J.N.
      Intra-operative haemorrhage by blunt versus sharp expansion of the uterine incision at caesarean delivery: a randomised clinical trial.
      • Rodriguez A.I.
      • Porter K.B.
      • O'Brien W.F.
      Blunt versus sharp expansion of the uterine incision in low-segment transverse cesarean section.
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      • Dodd J.M.
      • Anderson E.R.
      • Gates S.
      Surgical techniques for uterine incision and uterine closure at the time of caesarean section.
      The effect of blunt division of the uterine wall on the incidence of endometritis postcesarean delivery is also of concern.
      • Olsen M.A.
      • Butler A.M.
      • Willers D.M.
      • Gross G.A.
      • Devkota P.
      • Fraser V.J.
      Risk factors for endometritis after low transverse cesarean delivery.
      The aim of this review was to compare the impacts of sharp vs blunt hysterotomy on the primary outcome of maternal blood loss and the secondary outcomes of unintended extension, incidence of postoperative endometritis, injury to the neonate, postoperative pain, and operative time/time to delivery.

      Materials and Methods

      The Cochrane and Preferred Reporting Items for Systematic Review and Metaanalyses (PRISMA) guidelines were followed for the performance and reporting of this systematic review.
      • Higgins J.P.T.
      • Green S.
      Cochrane handbook for systematic reviews of interventions Version 5.1.0 [updated March 2011]. The Cochrane Collaboration 2011.
      • Moher D.
      • Liberati A.
      • Tetzlaff J.
      • Altman D.G.
      • Group P.
      Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement.

      Types of studies and outcomes considered

      All prospective randomized controlled trials (RCTs) that compared blunt vs sharp expansion of the initial uterine incision at transverse lower segment cesarean delivery were considered. Quasirandomized trials and studies that assessed vertical lower-segment or classic upper-segment uterine incisions were excluded. Ongoing or recently completed trials with no data yet available were noted for future analyses. Our primary outcome was maternal blood loss. Our secondary outcomes were incidence of extension, endometritis, neonatal morbidity, postoperative pain, and time to delivery.

      Search strategy

      A literature search of the Cochrane Central Register of Controlled Trials (The Cochrane Library 2012, Issue 4), Medline (via Ovid; 1948–April 2012), and Embase (via Ovid) (1947–April 2012) was performed in week 4, April 2012. The prospective search protocol for each database is given in Table 1. No language restrictions were used. All titles were assessed; where the abstract suggested a potentially eligible study, the full text was retrieved. Scopus was used to cross-reference the references and citation history of full-text articles. A search for ongoing or recently completed trials was performed in week 4, April 2012, with the Australia/New Zealand, United Kingdom, and United States Clinical Trials registries (www.anzctr.org.au, www.controlled-trials.com, www.clinicaltrials.gov, respectively). Studies were evaluated critically for design and risk of bias, according to criteria set out in the Cochrane handbook for systematic reviews of interventions.
      • Higgins J.P.T.
      • Green S.
      Cochrane handbook for systematic reviews of interventions Version 5.1.0 [updated March 2011]. The Cochrane Collaboration 2011.
      TABLE 1Search strategy using MeSH (CENTRAL, MEDLINE) and Emtree (EMBASE) terms
      No.CentralMedlineEmbase
      1MeSH descriptor cesarean delivery explode all treesexp cesarean section or caesarean section.mp or exp uterusexp cesarean section or caesarean section.mp or exp uterus
      2blunt or finger* or digital or sharp or instrument* or dissection or expansion or extensionblunt.mp or finger$.mp or digital.mp or sharp.mp or instrument$.mp or dissection.mp or expansion.mp or extension.mpblunt.mp or finger$.mp or digital.mp or sharp.mp or instrument$.mp or dissection.mp or expansion.mp or extension.mp
      3#1 and #2randomized controlled trial.pt or controlled clinical trial.pt or randomized.ab or placebo.ab or clinical trials as topic.sh or randomly.ab or trial.tirandomized controlled trial or controlled clinical trial or randomized.ab or placebo.ab or exp clinical trial(topic) or randomly.ab or trial.ti
      4and/1-3and/1-3
      5exp animals/not humans.shexp animals/not humans.sh
      64 not 54 not 5
      The asterisk and the dollar sign indicate truncation.
      ab, abstract; exp, explode; mp, multiple postings; pt, publication term; sh, subject heading; ti, title.
      Xu. Blunt vs sharp hysterotomy at cesarean delivery. Am J Obstet Gynecol 2013.

      Statistical analysis

      Data were extracted onto a standardized collection form by 2 independently working authors (L.X., A.C.) and entered into RevMan (version 5.1, 2011; The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark). Data were analyzed with the use of a random-effects metaanalysis (DerSimonian and Laird model) with risk ratio as the pooled estimate for dichotomous data and mean difference for continuous data. Mantel-Haenszel and inverse variance methods were used, respectively. Analysis was performed on an intention-to-treat basis. Substantial statistical heterogeneity was considered to be present when there was inconsistency between trials in the direction or magnitude of effects. This was assessed visually from the forest plots or when the I2 statistic was >50%, respectively. Statistical significance was defined as a probability value < .05.

      Results

      Evidence base

      The literature search returned 495 articles (Figure 1). From these, 4 RCTs (1731 patients) that reported data appropriate for the clinical question (Tables 2)
      • Hidar S.
      • Jerbi M.
      • Hafsa A.
      • Slama A.
      • Bibi M.
      • Khairi H.
      [The effect of uterine incision expansion at caesarean delivery on perioperative haemorrhage: a prospective randomised clinical trial].
      • Magann E.F.
      • Chauhan S.P.
      • Bufkin L.
      • Field K.
      • Roberts W.E.
      • Martin Jr, J.N.
      Intra-operative haemorrhage by blunt versus sharp expansion of the uterine incision at caesarean delivery: a randomised clinical trial.
      • Rodriguez A.I.
      • Porter K.B.
      • O'Brien W.F.
      Blunt versus sharp expansion of the uterine incision in low-segment transverse cesarean section.
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      were included in the study. One recently completed RCT had not yet reported the results, so it could not be included. Two studies were not RCTs.
      • Hameed N.
      • Ali M.A.
      Maternal blood loss by expansion of uterine incision at caesarean section: a comparison between sharp and blunt techniques.
      • Song S.H.
      • Oh M.J.
      • Kim T.
      • Hur J.Y.
      • Saw H.S.
      • Park Y.K.
      Finger-assisted stretching technique for cesarean section.
      Figure thumbnail gr1
      FIGURE 1PRISMA diagram of study identification, inclusion and exclusion
      Preferred reporting items for systematic review and metaanalyses flow diagram of study identification, inclusion, and exclusion of blunt vs sharp uterine expansion at cesarean delivery.
      PRISMA, Preferred Reporting Items for Systematic Review and Metaanalyses; RCT, randomized controlled trial.
      Xu. Blunt vs sharp hysterotomy at cesarean delivery. Am J Obstet Gynecol 2013.
      TABLE 2Study characteristics
      Study and locationWomen randomly assigned, nMean age at delivery, yInclusion criteriaExclusion criteriaIntervention
      Rodriguez et al,
      • Rodriguez A.I.
      • Porter K.B.
      • O'Brien W.F.
      Blunt versus sharp expansion of the uterine incision in low-segment transverse cesarean section.
      Florida
      286Blunt, 25.8; sharp, 25.7All patients undergoing primary or repeat transverse lower segment cesarean delivery; indications included arrest, malpresentation, previous cesarean delivery, fetal distressPatients unable to give informed consent because of emergency surgery or communication difficultiesUterine incision extended by fingers or control extended with bandage scissors; operator: 2nd- to 4th-year resident under direct supervision
      Magann et al,
      • Magann E.F.
      • Chauhan S.P.
      • Bufkin L.
      • Field K.
      • Roberts W.E.
      • Martin Jr, J.N.
      Intra-operative haemorrhage by blunt versus sharp expansion of the uterine incision at caesarean delivery: a randomised clinical trial.
      Mississippi
      975Blunt, 24.7; sharp, 24.4All patients undergoing primary or repeat transverse lower segment cesarean deliveryWomen declining participation, emergency surgery, use of vertical lower segment or classical upper segment uterine incisionUterine incision extended by fingers or control extended with scissors; 20 units oxytocin in 1000 mL Ringer's lactate rapid infusion after placental delivery; operator: 2nd- to 4th-year residents with assistance of attending staff
      Hidar et al,
      • Hidar S.
      • Jerbi M.
      • Hafsa A.
      • Slama A.
      • Bibi M.
      • Khairi H.
      [The effect of uterine incision expansion at caesarean delivery on perioperative haemorrhage: a prospective randomised clinical trial].
      Sousse, Tunisia
      300Blunt, 31.52; sharp, 31.6All patients with a singleton pregnancy undergoing transverse lower segment cesarean delivery at gestation of >36 wkAge <20 y; known coagulopathy; placenta previa; transverse presentations; preoperative bleedingUterine incision extended by fingers or control extended with scissors; manual placental delivery/in situ uterine repair; operator: 3rd- or 4th-year resident under senior supervision
      Sekhavat et al,
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      Yazd, Iran
      200Blunt, 24.3; sharp, 25.1Primiparous patients undergoing elective transverse lower segment cesarean delivery with fundal placentaSevere medical and surgical disorders; blood disorder/anemia; known thromboembolic disorder; multiple gestation; fetal macrosomia; polyhydramnios; emergency surgery for placental abruption; placenta previa, and severe preeclampsiaUterine incision extended by fingers or control extended with scissors; manual delivery of placenta, 10 units oxytocin in 500 mL normal saline solution >10 minutes; all patients underwent general anesthesia; operator: 2nd-year resident under supervision
      Xu. Blunt vs sharp hysterotomy at cesarean delivery. Am J Obstet Gynecol 2013.

      Study design

      Hysterotomy in the blunt expansion groups was performed after an initial 1-2cm incision was made through the uterine wall and then extended by insertion of the surgeon's index fingers laterally and cephalad. In the sharp expansion groups, the extension was achieved by cutting with bandage scissors laterally and cephalad.
      There were some differences in study design between the trials. Of the studies that specified cesarean technique, 1 study used the Pfannenstiel incision
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      and the other Joel-Cohen incision.
      • Hidar S.
      • Jerbi M.
      • Hafsa A.
      • Slama A.
      • Bibi M.
      • Khairi H.
      [The effect of uterine incision expansion at caesarean delivery on perioperative haemorrhage: a prospective randomised clinical trial].
      Two studies described the implementation of manual delivery of the placenta.
      • Hidar S.
      • Jerbi M.
      • Hafsa A.
      • Slama A.
      • Bibi M.
      • Khairi H.
      [The effect of uterine incision expansion at caesarean delivery on perioperative haemorrhage: a prospective randomised clinical trial].
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      An oxytocin infusion after placental delivery was used in 2 studies (20 units in 1000 mL Ringer's lactate; 10 units in 500 mL normal saline solution).
      • Magann E.F.
      • Chauhan S.P.
      • Bufkin L.
      • Field K.
      • Roberts W.E.
      • Martin Jr, J.N.
      Intra-operative haemorrhage by blunt versus sharp expansion of the uterine incision at caesarean delivery: a randomised clinical trial.
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      Prophylactic antibiotics were given to all patients in 1 study and to patients in active labor after cord clamping in another.
      • Hidar S.
      • Jerbi M.
      • Hafsa A.
      • Slama A.
      • Bibi M.
      • Khairi H.
      [The effect of uterine incision expansion at caesarean delivery on perioperative haemorrhage: a prospective randomised clinical trial].
      • Rodriguez A.I.
      • Porter K.B.
      • O'Brien W.F.
      Blunt versus sharp expansion of the uterine incision in low-segment transverse cesarean section.
      Women who underwent lower-segment cesarean delivery were included in these trials; however, there were differing additional enrolment criteria. Three studies excluded women who underwent emergency surgery.
      • Magann E.F.
      • Chauhan S.P.
      • Bufkin L.
      • Field K.
      • Roberts W.E.
      • Martin Jr, J.N.
      Intra-operative haemorrhage by blunt versus sharp expansion of the uterine incision at caesarean delivery: a randomised clinical trial.
      • Rodriguez A.I.
      • Porter K.B.
      • O'Brien W.F.
      Blunt versus sharp expansion of the uterine incision in low-segment transverse cesarean section.
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      One study enrolled exclusively nulliparous women because of the risk of uterine inertia with multiparity.
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      General anesthesia was also used in all patients in this study.
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      Two studies excluded patients with known coagulopathy and multiple gestations.
      • Hidar S.
      • Jerbi M.
      • Hafsa A.
      • Slama A.
      • Bibi M.
      • Khairi H.
      [The effect of uterine incision expansion at caesarean delivery on perioperative haemorrhage: a prospective randomised clinical trial].
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      From the 2 studies that provided data, the most common indications for cesarean delivery were arrest of labor, malpresentation, previous cesarean delivery, and fetal distress.
      • Rodriguez A.I.
      • Porter K.B.
      • O'Brien W.F.
      Blunt versus sharp expansion of the uterine incision in low-segment transverse cesarean section.
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.

      Critical appraisal of included RCTs

      All 4 trials were judged to have low overall risk of bias (Figure 2). Two trials had a high risk of detection bias in subjective outcome measures because of lack of blinding.
      • Magann E.F.
      • Chauhan S.P.
      • Bufkin L.
      • Field K.
      • Roberts W.E.
      • Martin Jr, J.N.
      Intra-operative haemorrhage by blunt versus sharp expansion of the uterine incision at caesarean delivery: a randomised clinical trial.
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      One study had an unclear risk of selection bias because the authors did not specify the method of randomization; however, there were no statistically significant differences between the experimental and control groups in all recorded characteristics.
      • Rodriguez A.I.
      • Porter K.B.
      • O'Brien W.F.
      Blunt versus sharp expansion of the uterine incision in low-segment transverse cesarean section.
      Figure thumbnail gr2
      FIGURE 2Summary assessment demonstrates the low risk of bias of included randomized controlled trials
      Adapted, with permission, from the Cochrane handbook (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark).
      Green denotes low risk; yellow denotes unclear risk; red denotes high risk.
      Xu. Blunt vs sharp hysterotomy at cesarean delivery. Am J Obstet Gynecol 2013.

      Primary outcome: impact on maternal blood loss

      Mean drop in hematocrit level

      Three studies evaluated maternal blood loss by reduction in hematocrit level before and after the operation.
      • Hidar S.
      • Jerbi M.
      • Hafsa A.
      • Slama A.
      • Bibi M.
      • Khairi H.
      [The effect of uterine incision expansion at caesarean delivery on perioperative haemorrhage: a prospective randomised clinical trial].
      • Magann E.F.
      • Chauhan S.P.
      • Bufkin L.
      • Field K.
      • Roberts W.E.
      • Martin Jr, J.N.
      Intra-operative haemorrhage by blunt versus sharp expansion of the uterine incision at caesarean delivery: a randomised clinical trial.
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      Magann et al
      • Magann E.F.
      • Chauhan S.P.
      • Bufkin L.
      • Field K.
      • Roberts W.E.
      • Martin Jr, J.N.
      Intra-operative haemorrhage by blunt versus sharp expansion of the uterine incision at caesarean delivery: a randomised clinical trial.
      compared immediate preoperative hematocrit level with that 48 hours after the operation. A statistically significant reduction in hematocrit drop was found favoring the blunt group (P = .003). Consistent with this, the incidence of women who experienced a >10% decrease in hematocrit level was also significantly smaller in the blunt, rather than the sharp, group (P = .03; author calculated with χ2 test).
      Hidar et al
      • Hidar S.
      • Jerbi M.
      • Hafsa A.
      • Slama A.
      • Bibi M.
      • Khairi H.
      [The effect of uterine incision expansion at caesarean delivery on perioperative haemorrhage: a prospective randomised clinical trial].
      compared immediate preoperative hematocrit level with that 24-48 hours after the operation and found no difference in the average reduction in hematocrit level between the 2 groups (P = .58). The incidence of >10% reduction in hematocrit level was also comparable (P > .05).
      Sekhavat et al
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      measured hematocrit level immediately before the operation and 24 hours after the operation. A decreased drop in pre- to post-operative hematocrit level in the blunt group that was detected when the data were compared with the sharp group was significant (P < .05).
      Combined results from the 3 trials revealed a trend that favored blunt hysterotomy for reduced drop in hematocrit level after the operation (Figure 3) ; however, this did not reach statistical significance (mean difference [MD], −0.86%; 95% CI, −2.04 to 0.32; 3 trials; 1445 patients). There was substantial statistical heterogeneity across studies (I2 = 91%).
      Figure thumbnail gr3
      FIGURE 3Mean drop in hematocrit level
      df, degrees of freedom; IV, inverse variance.
      Xu. Blunt vs sharp hysterotomy at cesarean delivery. Am J Obstet Gynecol 2013.

      Mean drop in hemoglobin

      Three studies recorded change in pre- and postoperative hemoglobin levels.
      • Hidar S.
      • Jerbi M.
      • Hafsa A.
      • Slama A.
      • Bibi M.
      • Khairi H.
      [The effect of uterine incision expansion at caesarean delivery on perioperative haemorrhage: a prospective randomised clinical trial].
      • Rodriguez A.I.
      • Porter K.B.
      • O'Brien W.F.
      Blunt versus sharp expansion of the uterine incision in low-segment transverse cesarean section.
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      Rodriguez et al
      • Rodriguez A.I.
      • Porter K.B.
      • O'Brien W.F.
      Blunt versus sharp expansion of the uterine incision in low-segment transverse cesarean section.
      found no difference in mean hemoglobin level decrease when they compared the hemoglobin level that was measured at admission and the 24 hours postoperative measurement in the 2 groups (P = .08; author calculated with unpaired t test).
      Hidar et al
      • Hidar S.
      • Jerbi M.
      • Hafsa A.
      • Slama A.
      • Bibi M.
      • Khairi H.
      [The effect of uterine incision expansion at caesarean delivery on perioperative haemorrhage: a prospective randomised clinical trial].
      found the 2 groups comparable in mean hemoglobin level drop when they compared the values that were measured immediately before and 24-48 hours after surgery (P = .51).
      Sekhavat et al
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      found a significantly smaller mean hemoglobin level difference when they compared the values measured before and 24 hours after surgery in the blunt group (P < .05).
      Pooled results showed a trend toward a reduced drop in hemoglobin level that favored the blunt dissection group (Figure 4), although this was not statistically significant (MD, 7.41 g/L; 95% CI, −20.53 to 5.72; 3 trials; 786 patients). There was substantial heterogeneity across studies (I2 = 98%).
      Figure thumbnail gr4
      FIGURE 4Mean drop in hemoglobin level
      df, degrees of freedom; IV, inverse variance.
      Xu. Blunt vs sharp hysterotomy at cesarean delivery. Am J Obstet Gynecol 2013.

      Requirement for blood transfusion

      Three studies reported on the number of patients who required blood transfusion after surgery.
      • Hidar S.
      • Jerbi M.
      • Hafsa A.
      • Slama A.
      • Bibi M.
      • Khairi H.
      [The effect of uterine incision expansion at caesarean delivery on perioperative haemorrhage: a prospective randomised clinical trial].
      • Magann E.F.
      • Chauhan S.P.
      • Bufkin L.
      • Field K.
      • Roberts W.E.
      • Martin Jr, J.N.
      Intra-operative haemorrhage by blunt versus sharp expansion of the uterine incision at caesarean delivery: a randomised clinical trial.
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      Magann et al
      • Magann E.F.
      • Chauhan S.P.
      • Bufkin L.
      • Field K.
      • Roberts W.E.
      • Martin Jr, J.N.
      Intra-operative haemorrhage by blunt versus sharp expansion of the uterine incision at caesarean delivery: a randomised clinical trial.
      specified a hematocrit level of <24% and hemodynamic instability as criteria for transfusion. A significantly smaller number of women in the blunt group than in the sharp group required transfusion (P = .03; author calculated with Fisher exact test).
      Hidar et al
      • Hidar S.
      • Jerbi M.
      • Hafsa A.
      • Slama A.
      • Bibi M.
      • Khairi H.
      [The effect of uterine incision expansion at caesarean delivery on perioperative haemorrhage: a prospective randomised clinical trial].
      did not specify indications for transfusion, and no patients required transfusion in this study.
      Sekhavat et al
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      described a hematocrit level of <24% and a change of ≥10% in hematocrit level from admission to the postpartum period as indication for transfusion. There was no difference detected in requirement for transfusion between the 2 groups (P > .05).
      Combined data suggested a strong trend towards decreased incidence of blood transfusion in patients who underwent blunt dissection, although this did not reach significance (relative risk, 0.31; 95% CI, 0.08–1.19; 3 trials; 1445 patients). There was low statistical heterogeneity (I2 = 0%; Figure 5).
      Figure thumbnail gr5
      FIGURE 5Requirement for blood transfusion
      df, degrees of freedom; M-H, Mantel-Haenszel.
      Xu. Blunt vs sharp hysterotomy at cesarean delivery. Am J Obstet Gynecol 2013.

      Blood loss by estimated volume

      Two studies examined blood loss by estimated volume.
      • Magann E.F.
      • Chauhan S.P.
      • Bufkin L.
      • Field K.
      • Roberts W.E.
      • Martin Jr, J.N.
      Intra-operative haemorrhage by blunt versus sharp expansion of the uterine incision at caesarean delivery: a randomised clinical trial.
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      Magann et al
      • Magann E.F.
      • Chauhan S.P.
      • Bufkin L.
      • Field K.
      • Roberts W.E.
      • Martin Jr, J.N.
      Intra-operative haemorrhage by blunt versus sharp expansion of the uterine incision at caesarean delivery: a randomised clinical trial.
      measured volume by the estimation of the surgeon and attending staff based on the blood in the suction apparatus, plastic steridrapes, lap pads, and sponges. A significantly greater volume of intraoperative hemorrhage was recorded in the sharp compared with blunt group (P = .001).
      Sekhavat et al
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      measured volume by evaluating blood in the suction apparatus and weight difference of pre- and postoperative lap pads and sponges. They found that the volume of blood lost was significantly larger in the sharp compared with blunt group (P < .05).
      Metaanalysis of composite data revealed a reduced estimated volume of blood loss that favored the blunt group that was statistically significant (MD, −55.00 mL; 95% CI, −79.48 to −30.52; 2 trials; 1145 patients) with substantial heterogeneity between studies (I2 = 51%; Figure 6).
      Figure thumbnail gr6
      FIGURE 6Blood loss by estimated volume
      df, degrees of freedom; IV, inverse variance.
      Xu. Blunt vs sharp hysterotomy at cesarean delivery. Am J Obstet Gynecol 2013.

      Secondary outcomes

      Incidence of extension

      Three studies evaluated the incidence of unintended extension.
      • Magann E.F.
      • Chauhan S.P.
      • Bufkin L.
      • Field K.
      • Roberts W.E.
      • Martin Jr, J.N.
      Intra-operative haemorrhage by blunt versus sharp expansion of the uterine incision at caesarean delivery: a randomised clinical trial.
      • Rodriguez A.I.
      • Porter K.B.
      • O'Brien W.F.
      Blunt versus sharp expansion of the uterine incision in low-segment transverse cesarean section.
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      Rodriguez et al
      • Rodriguez A.I.
      • Porter K.B.
      • O'Brien W.F.
      Blunt versus sharp expansion of the uterine incision in low-segment transverse cesarean section.
      defined extension as any defect of >2 cm outside the original incision. The 2 groups were similar in incidence and length of extensions (P = .61). There were no cases of injury to the cervix, vagina, or broad ligament.
      Magann et al
      • Magann E.F.
      • Chauhan S.P.
      • Bufkin L.
      • Field K.
      • Roberts W.E.
      • Martin Jr, J.N.
      Intra-operative haemorrhage by blunt versus sharp expansion of the uterine incision at caesarean delivery: a randomised clinical trial.
      defined extension as any defect that was found beyond the original incision. A significantly decreased risk of any extension in the blunt, compared with sharp, group was detected (P < .0001; author calculated with χ2 test). However, there was no difference in the number of broad ligament and cervical lacerations (P = .06 and P = .14, respectively).
      Sekhavat et al
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      recorded no significant differences in the number of extensions between the 2 groups (P > .05). There were no extensions into the broad ligament or cervix.
      Pooled data from 3 studies showed a strong trend toward a reduced incidence of unintended extension in the blunt, compared with sharp, group, which was not significant (relative risk, 0.57; 95% CI, 0.28–1.17; 3 trials; 1431 patients), but with considerable heterogeneity between studies (I2 = 74%; Figure 7).
      Figure thumbnail gr7
      FIGURE 7Incidence of unintended extensions
      df, degrees of freedom; M-H, Mantel-Haenszel.
      Xu. Blunt vs sharp hysterotomy at cesarean delivery. Am J Obstet Gynecol 2013.

      Endometritis

      This outcome was reported in 3 studies.
      • Hidar S.
      • Jerbi M.
      • Hafsa A.
      • Slama A.
      • Bibi M.
      • Khairi H.
      [The effect of uterine incision expansion at caesarean delivery on perioperative haemorrhage: a prospective randomised clinical trial].
      • Magann E.F.
      • Chauhan S.P.
      • Bufkin L.
      • Field K.
      • Roberts W.E.
      • Martin Jr, J.N.
      Intra-operative haemorrhage by blunt versus sharp expansion of the uterine incision at caesarean delivery: a randomised clinical trial.
      • Rodriguez A.I.
      • Porter K.B.
      • O'Brien W.F.
      Blunt versus sharp expansion of the uterine incision in low-segment transverse cesarean section.
      Rodriguez et al
      • Rodriguez A.I.
      • Porter K.B.
      • O'Brien W.F.
      Blunt versus sharp expansion of the uterine incision in low-segment transverse cesarean section.
      diagnosed endometritis on the basis of fever, foul smelling lochia, and uterine and parametrial tenderness with no other focus of infection. No difference was found between the 2 groups (P = .81).
      Magann et al
      • Magann E.F.
      • Chauhan S.P.
      • Bufkin L.
      • Field K.
      • Roberts W.E.
      • Martin Jr, J.N.
      Intra-operative haemorrhage by blunt versus sharp expansion of the uterine incision at caesarean delivery: a randomised clinical trial.
      did not describe diagnostic criteria for endometritis. The 2 groups were comparable in the incidence of endometritis (P = .12; author calculated with χ2 test).
      Hidar et al
      • Hidar S.
      • Jerbi M.
      • Hafsa A.
      • Slama A.
      • Bibi M.
      • Khairi H.
      [The effect of uterine incision expansion at caesarean delivery on perioperative haemorrhage: a prospective randomised clinical trial].
      defined endometritis as leukocytosis with high-grade fever (>38.5°C) that lasted >6 hours that occurred >24 hours after delivery. The incidence of endometritis was similar in the 2 groups (P > .99).
      There was no significant difference in the number of women who experienced endometritis after the operation across these trials (relative risk, 0.92; 95% CI, 0.75–1.13; 3 trials; 1531 patients). Heterogeneity was low (I2 = 0%; Figure 8).
      Figure thumbnail gr8
      FIGURE 8Incidence of endometritis
      df, degrees of freedom; M-H, Mantel-Haenszel.
      Xu. Blunt vs sharp hysterotomy at cesarean delivery. Am J Obstet Gynecol 2013.

      Neonatal injury

      No studies reported on the incidence of intraoperative injury to the neonate.

      Postoperative pain

      No studies compared differences in maternal postoperative pain.

      Operative time/time to delivery

      Rodriguez et al
      • Rodriguez A.I.
      • Porter K.B.
      • O'Brien W.F.
      Blunt versus sharp expansion of the uterine incision in low-segment transverse cesarean section.
      reported on time to delivery, and Sekhavat et al
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      recorded total operative time.
      Rodriguez et al
      • Rodriguez A.I.
      • Porter K.B.
      • O'Brien W.F.
      Blunt versus sharp expansion of the uterine incision in low-segment transverse cesarean section.
      found no differences in the time from the start of surgery to the delivery of the neonate between the sharp (mean, 11.7 min) and blunt groups (11.5 min; P = .72; author calculated with unpaired t test).
      Similarly, Sekhavat et al
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      found that there was no difference in total operating time when they compared the sharp (mean, 30.7 min) and blunt (mean, 27.9 min) hysterotomy (P > .05).

      Comment

      The effect of sharp vs blunt hysterotomy on maternal blood loss, injury to local structures, and occurrence of endometritis were evaluated in this review. As far as the authors are aware, this is the most comprehensive attempt to review the literature systematically in relation to this clinical question.
      Five randomized controlled trials were identified, of which data from 4 relatively heterogeneous studies were available for metaanalysis (1731 patients).
      • Hidar S.
      • Jerbi M.
      • Hafsa A.
      • Slama A.
      • Bibi M.
      • Khairi H.
      [The effect of uterine incision expansion at caesarean delivery on perioperative haemorrhage: a prospective randomised clinical trial].
      • Magann E.F.
      • Chauhan S.P.
      • Bufkin L.
      • Field K.
      • Roberts W.E.
      • Martin Jr, J.N.
      Intra-operative haemorrhage by blunt versus sharp expansion of the uterine incision at caesarean delivery: a randomised clinical trial.
      • Rodriguez A.I.
      • Porter K.B.
      • O'Brien W.F.
      Blunt versus sharp expansion of the uterine incision in low-segment transverse cesarean section.
      • Sekhavat L.
      • Dehghani Firouzabadi R.
      • Mojiri P.
      Effect of expansion technique of uterine incision on maternal blood loss in cesarean section.
      It was found that the estimated volume of blood loss was significantly less in the blunt than the sharp dissection group. Trends that favored blunt dissection for reduced blood loss (measured through laboratory values and maternal requirement for transfusion) and unintended extensions were also detected; however, these did not reach statistical significance. The incidence of endometritis occurred equally after either procedure.
      From collated evidence in the current literature, it appears that blunt dissection of the hysterotomy at cesarean delivery is superior to sharp dissection. Three of 4 proxy measures of blood loss favored the use of blunt dissection without reaching statistical significance. The fourth measure (blood loss by estimation of volume) was significantly reduced with the use of blunt dissection. However, volume estimation methods that were used in the studies were partly subjective and did not account for amniotic or other fluids that had also accumulated in the suction apparatus and absorptive material. This measure therefore is subject to a degree of inaccuracy and detection bias because of the lack of assessor blinding.
      • Rath W.H.
      Postpartum hemorrhage: update on problems of definitions and diagnosis.
      With further data from the recently completed Turkish RCT (535 women) (unpublished data) and future studies, the true significance of this trend could be better elucidated.
      The strength of any systematic review lies in the quality of the studies that are examined. We used a sensitive prospective search strategy with no language limitations, extensive cross-referencing, and a search for recently completed or ongoing trials.
      Critical evaluation of the RCTs that were included in this review determined a low overall risk of bias with good internal validity. Results across studies for some outcomes were able to be synthesized convincingly for quantitative metaanalysis; however, there was notable statistical heterogeneity across studies in other outcomes. The small number of studies that were involved prohibited further investigation with sensitivity analysis. The differences between study findings likely stem from a variation in patient selection, surgical techniques, and diverse peripartum management (eg, use of oxytocin postplacental delivery).
      It has been suggested in the literature that blunt dissection of the uterus may contribute to a faster operative time and time to delivery of the infant.
      • Song S.H.
      • Oh M.J.
      • Kim T.
      • Hur J.Y.
      • Saw H.S.
      • Park Y.K.
      Finger-assisted stretching technique for cesarean section.
      With only one of the studies examining this outcome, there were limited data found that related to the effects of hysterotomy technique on the speed of execution. There are some data from a nonrandomized, retrospective study that compared mean operative times that could not be included in this review.
      • Song S.H.
      • Oh M.J.
      • Kim T.
      • Hur J.Y.
      • Saw H.S.
      • Park Y.K.
      Finger-assisted stretching technique for cesarean section.
      Another suggested theoretic advantage of blunt dissection is decreased injury to the neonate.
      • Smith J.F.
      • Hernandez C.
      • Wax J.R.
      Fetal laceration injury at cesarean delivery.
      This outcome has not been evaluated in any studies to date. It would be valuable to explore these aspects in future research.
      The results of this systematic review revealed blunt dissection of the uterine incision at lower-segment cesarean delivery is associated with a significant reduction in blood loss when compared with sharp dissection. Blood loss by estimation of volume was significantly lower with the use of blunt dissection. Laboratory-based outcomes of drop in hemoglobin/hematocrit level and maternal requirement for blood transfusion supported this finding but did not reach statistical significance. The addition of data from a new unpublished large trial could further clarify the clinical differences between the 2 techniques.

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