Uterine necrosis during pregnancy following exploratory laparotomy

Background

Uterine necrosis is a condition most commonly seen in the postpartum period as a complication of surgical methods used to control postpartum haemorrhage, including uterine artery embolisation, compression sutures and uterine artery ligation.1–3 The risk of uterine necrosis appears to be increased when a combination of these methods is used simultaneously.1 As this condition is rare, its precise incidence is uncertain. A review by Poujade et al identified 19 cases of uterine necrosis following pelvic embolisation for postpartum haemorrhage spanning from 1985 to 2013, of which four cases had partial uterine involvement.4 In these cases, management typically included total (78%) or subtotal (10%) hysterectomy, with 15% also undergoing partial cystectomy for associated bladder necrosis. A more recent review of complications of uterine artery embolisation after postpartum haemorrhage demonstrated uterine necrosis in 11 of 117 patients. Of these, two patients required hysterectomy, and the remainder were managed with serial pelvic ultrasound every 6–12 months.2

Antepartum uterine necrosis has been described as a theoretical complication of incarceration of the retroverted uterus between the symphysis pubis and sacral promontory.5 Otherwise, cases of its occurrence during pregnancy are scarce. Accordingly, the natural history and optimal management of uterine necrosis occurring during pregnancy remain unknown. In this report, we describe a case of uterine necrosis occurring as a complication of laparotomy for ovarian torsion during pregnancy.

Case presentation

A gravida 3, para 2 at 33 weeks and 4 days of gestation presented to a community hospital with right-sided abdominal pain. Physical examination was notable for right lower quadrant guarding and rebound, and pelvic ultrasound showed an 8 cm adnexal mass, concerning for adnexal torsion. She underwent exploratory laparotomy, which confirmed ovarian torsion. On entry into the abdomen, haemoperitoneum was noted. A haemorrhagic ovarian cyst was dissected off the ovary and uterus, after which haemostatic sutures were placed into the uterine wall to control surface bleeding adjacent to the dissection. Additional bleeding from engorged uterine vessels along the right uterine sidewall was controlled by suture placement, and electrocautery was also used to manage serosal bleeding. Estimated blood loss was 750 mL; given postoperative haemoglobin drop from 102 g/L to 67 g/L, this was thought to be an underestimation. She received three units of packed red cells for symptomatic acute blood loss anaemia and her haemoglobin stabilised. She also received antenatal corticosteroids for fetal lung maturity on postoperative days 0 and 1. Fetal monitoring was reassuring throughout this hospitalisation. She was discharged on postoperative day 4. Pathological examination of the surgical specimen confirmed an 8.7 cm haemorrhagic mucinous cystadenoma.

The patient presented to our institution on postoperative day 7, at 34 weeks and 3 days of gestation, with persistent, severe right abdominal pain. At the time of presentation, she had normal vital signs: the temperature was 36.7°C, blood pressure was 119/69 mm Hg, pulse was 96 beats/min, respiratory rate was 18 breaths/min and SpO₂ was >96% on room air. On physical examination, her abdomen was diffusely tender to palpation without rebound or guarding. External fetal heart monitoring was reassuring. Regular contractions were noted on tocometry and correlated with the worsening of her abdominal pain. Her cervix was 1 cm dilated and remained stable over serial cervical examinations.

Investigations

Complete blood count (CBC), comprehensive metabolic panel (CMP), lipase, haptoglobin and urinalysis were obtained, notable for mild transaminitis (aspartate aminotransferase 89 U/L and alanine transaminase 76 U/L). The remainder of her laboratories were normal. She underwent a CT abdomen/pelvis with intravenous contrast, which revealed mild stranding adjacent to the right uterine body at the prior surgical site and moderate stool burden. No clear cause of her pain was identified. The patient was admitted and received intravenous opioids along with stool softeners and laxatives; she had a bowel movement and her pain improved significantly. Her transaminitis spontaneously resolved on follow-up. She was discharged home after 3 days.

The patient initially did well at home, though she continued to have intermittent episodes of abdominal pain requiring acetaminophen and hydrocodone. At 35 weeks and 5 days of gestation, the patient had a fetal growth ultrasound performed that showed normal amniotic fluid volume and an estimated fetal weight of 3219 g (90th percentile for gestational age by Hadlock formula). No pelvic free fluid or abnormalities of the uterus, cervix, ovaries or adnexa were seen.

Differential diagnosis

The differential diagnosis of postoperative abdominal pain in a pregnant patient included intra-abdominal bleeding, haematoma, bowel or bladder injury, surgical site infection or pelvic abscess. Uterine rupture due to myometrial injury was considered given the involvement of the uterine body during the initial surgery, but felt to be less likely in the setting of reassuring fetal heart tracing and no prior uterine surgery. Preterm labour was also considered; however, the patient had no cervical change over serial examinations. Once laboratory results showed a mild transaminitis, the team also considered liver injury, cholelithiasis, pre-eclampsia and HELLP syndrome. The patient met no blood pressure or laboratory criteria for a pregnancy-induced hypertensive disorder. Additionally, a CT scan demonstrated expected inflammatory changes at the surgical site, without definitive evidence to support any of the differential diagnoses. After several days of admission for serial abdominal examinations, pain control and a bowel regimen, her symptoms improved enough for discharge. She did well in the intervening 2 weeks, further supporting a benign cause of her abdominal pain; uterine necrosis was not suspected by the treating team prior to diagnosis.

Treatment

The patient presented to our institution again at 36 weeks and 6 days with regular painful contractions and worsened abdominal pain. Her cervix was 1 cm dilated, and she had no peritoneal signs on abdominal examination. CBC, CMP, lipase and urinalysis were normal. Fetal heart tracing was notable for intermittent late decelerations. She was admitted for delivery due to category II fetal heart tracing near term. Induction was initiated with the cervical ripening balloon, oxytocin infusion and artificial rupture of membranes. After 12 hours, the fetal heart rate was non-reassuring, with tachycardia up to 180 beats/min, minimal variability, intermittent late decelerations and pseudo-sinusoidal pattern. Despite resuscitative measures and initiation of empirical ampicillin and gentamicin for suspected chorioamnionitis, the patient ultimately underwent emergent low transverse caesarean delivery for prolonged fetal bradycardia. A male neonate weighing 3110 g was delivered with Apgar scores of 7, 8 and 9 at 1, 5 and 10 min of life, respectively.

At the time of uterine exteriorisation for hysterotomy repair, a 5 cm region of apparent myometrial necrosis with surrounding hyperaemia was noted within the right uterine body (figure 1). Cultures and biopsy of this area were collected. Intraoperative consultation with a gynecologic-oncologist was obtained, and the decision was made to leave the uterus in situ without resection of the necrotic area. The remainder of the caesarean delivery was complicated by uterine atony requiring intramuscular methylergonovine, carboprost and placement of a B-Lynch suture, with an estimated blood loss of 800 mL.

Figure 1

A focal area of uterine necrosis noted at the time of caesarean delivery.

Postoperatively, the patient continued empirical intravenous antibiotics, consisting of ampicillin, gentamicin and clindamycin. On postoperative day 2, she had a transient fever of 39.2°C, but then remained afebrile for the remainder of her postpartum hospitalisation. Pathological examination of uterine biopsy confirmed necrosis. Cultures from this region grew Staphylococcus lugdunensis and blood cultures resulted in no bacterial growth. On repeat CT scans, no abscess or alternative source of infection was identified. With input from infectious disease, her antibiotic regimen was continued for 7 days postoperatively.

Outcome and follow-up