Unexplained Spontaneous Complete Uterine Rupture in the Second Trimester: A Rare Event. Case Report and Literature Review

Introduction

Uterine rupture is a rare catastrophic obstetric event with significant consequences. The majority of cases reported in the literature are term pregnancies, and are usually associated with prior uterine surgery, trauma, induction of labor, or abnormal placenta. Spontaneous rupture of an unscarred uterus, especially in the absence of known risk factors, is exceedingly rare, and is almost unheard of in the second trimester.

An extremely unusual case of complete uterine rupture in an otherwise uncomplicated pregnancy in the early second trimester with no apparent risk factors, is presented.

Case

The patient was a 21-year-old woman, gravida 3. Her first pregnancy had ended in a spontaneous miscarriage at 10 weeks of gestation, following which there was neither any history of uterine curettage nor any excessive prolonged bleeding. The second pregnancy continued to term, and the patient had an uneventful normal vaginal delivery. However, no medical records of previous pregnancies were available. In her third pregnancy, the present case, she presented to the emergency department at 16 weeks of gestation with complaints of severe abdominal pain associated with fainting episodes and vomiting. There was no history of use of any uterotonic agents or any uterine instrumentation in this pregnancy.

The patient looked acutely ill, pale, and in respiratory distress. Her pulse was 140 beats per minute and blood pressure was 94/60 mm Hg. On examination, her abdomen was distended, tense, and diffusely tender. On pelvic examination, the cervical os was closed, without bleeding. There was cervical tenderness and the uterus was difficult to outline. The pouch of Douglas was bulging and tender.

Her hemoglobin was 4 gm% and white blood cell count was 10,500/mm³. An urgent ultrasound revealed massive intraperitoneal fluid and a fetus of ∼16 weeks of gestation, with no cardiac activity lying outside the uterine cavity. A provisional diagnosis of ruptured uterine cornual pregnancy was made.

A decision to perform emergency laparotomy was made. With the patient under general anesthesia, a midline vertical incision was made, and immediately, a large hemoperitoneum was noted. Approximately 2 L of blood and blood clots were removed from the abdomen. A 4 cm thick defect was noted at the uterine fundus. The fetus and placenta, which were loosely adherent to the omentum attached to the uterine defect, were extracted and sent for pathologic examination (Fig. 1). There was no abnormal vasculature at the margins of the rupture site. The uterine cavity was explored and found to be free of any fetal parts, placenta, or membranes. Both cornua of the uterus were clearly identified separately from the rupture, ruling out a ruptured cornual pregnancy. Both fallopian tubes and ovaries were normal. The uterine defect was repaired in three layers and Gelfoam^® was used to cover the repaired tissue.

OPEN IN VIEWER

FIG. 1.

Ruptured uterus, with both fallopian tubes held by Babcock forceps, and a single fetus with its attached cord and part of the omentum.

The histopathologic examination revealed a normal placenta and a fetus corresponding to 16 weeks of gestation. Two units of packed red blood cells were transfused intraoperatively. The patient received three additional units of packed red blood cells and two units of fresh frozen plasma in the postoperative period. She was given broad spectrum parenteral antibiotics for 5 days in addition to analgesics and anti-inflammatory agents.

Results

This patient's postoperative period was stable. Her sutures were removed after 1 week and she was discharged in a stable condition.

Discussion

Uterine rupture is a rare, life-threatening event in obstetrics. It usually occurs in the presence of a uterine scar, often from a previous cesarean delivery, and less commonly from myomectomy, surgical abortion, or amniocentesis.

Although the incidence of uterine rupture with a uterine scar is ∼1% (previous low transverse incision) or 4%–9% (previous classical incision), rupture of an unscarred uterus is a very rare obstetric complication, with an estimated incidence of 1 in 8000–15,000 deliveries.^1,2

Risk factors for uterine rupture in an unscarred uterus include use of uterotonic agents, abnormal placentation (e.g., placenta accreta or percreta, or cornual pregnancies), uterine anomalies, grand multiparity, maternal connective tissue disorders, and trauma (e.g., fundal pressure, instrumental forceps delivery, or violent nonobstetric event). ³

This patient had an unscarred uterus and did not have any of the abovementioned risk factors for uterine rupture. Moreover, almost all cases of uterine rupture (in unscarred uterus and without risk factors) that have been reported in the literature have occurred in the third trimester, during labor, and involve the lower or posterior uterine segment. ⁴ The extremely rare case described here was of a second trimester rupture involving the uterine fundus. ¹

A review of the literature beginning in 1946 identified only 6 cases of second trimester spontaneous uterine rupture. ³ However, all these cases had one or another risk factor; for example, 3 patients had had a prior myomectomy, 1 had placenta percreta, another had a bicornuate uterus, and 1 had a history of diethylstibesterol exposure. Isolated case reports of second trimester uterine rupture caused by uterotonic agents have also been reported.^5,6

A literature search for all reported cases of second trimester uterine rupture in the absence of risk factors revealed only 1 case report, but even that patient did not have a normal prenatal course. She was a multipara (para 3), had conceived with a copper intrauterine device, which was removed at 11 weeks of gestation, and had a twin pregnancy with 1 vanishing twin at 7 weeks of gestation. ¹

The situation reported here is extremely rare, for several reasons. First, the patient had an unscarred uterus. Even though she had had a previous miscarriage, it was spontaneous, and no surgical intervention had occurred. Moreover, she had had one normal uneventful vaginal delivery following the miscarriage.

Second, the rupture occurred in second trimester. Third, the rupture occurred prior to labor or induction, and there had been no use of uterotonic agents. Finally, the rupture involved the fundus of the uterus.

Conclusions

The present case highlights a few important lessons for all medical practitioners.

Although spontaneous uterine rupture in the second trimester is extremely rare, it can occur. An unscarred uterus should not be considered “immune” to spontaneous uterine rupture at any period of gestation.

Even in the absence of classical risk factors, uterine rupture should be considered as a possibility in a pregnant woman with severe abdominal pain, regardless of period of gestation.

Prompt diagnosis and management are essential to prevent maternal morbidity and mortality from this catastrophic event.

Moreover, knowledge of this clinical entity would help practitioners exercise caution when planning second trimester inductions.