Rare causes of acute abdomen in pregnancy: “ultrasound to the rescue”. A review of two cases

Introduction

Acute abdomen is defined as any serious intra-abdominal condition for which emergency surgery must be considered [1]. It is a rare entity with incidence ranging from 1:500 to 1:635 pregnancies [2, 3].

About 0.2% of pregnancies are complicated with non-obstetrical abdominal pathology in need of surgery [4]. Appendicitis accounts for 70.1% (including 10% complicated by perforating peritonitis) of the diseases that cause acute abdomen, followed by ileus (21.0%), torsion of an ovarian cyst (5.3%), and acute cholecystitis and cholangitis (3.6%) [5]; others are acute pancreatitis [6] and urethrolith [7].

Physiological and anatomical changes in pregnancy affect symptoms and physical signs elicited during examination. The physiological changes are related to the effect of progesterone on smooth muscles. Anatomical changes are related to the upward movement of the gravid uterus with increasing gestational age. This makes it difficult to localize the pain and may mask or delay peritoneal signs [8]. Laxity of the anterior abdominal wall may also delay peritoneal signs. The appendix is gradually displaced above McBurney’s point with horizontal rotation of its base. These changes can lead to misdiagnosis and delayed treatment.

Sonography remains the initial imaging study of choice in the evaluation of the pregnant woman presenting with acute abdomen [1]. It is a safe, relatively inexpensive, and versatile technique that is readily available [1]. It is non-invasive to both mother and fetus, and large amount of information can be obtained by this simple procedure [9]. Magnetic resonance imaging (MRI) is another diagnostic modality that has not been shown to have any deleterious effects on pregnancy and should be used where feasible [10]. It is the only diagnostic modality that clearly delineates the ovarian origin as well as the nature of the mass [11, 12]. Other imaging modalities, e.g., abdominal x-rays and computed tomography scan have limited utility in pregnancy because of fetal exposure to radiation. However, if the condition of the mother and fetus requires emergency treatment or surgery, x-rays should be used regardless of the pregnancy [9].

The possibility of pre-term labor after non-obstetric surgery during pregnancy increases with increasing gestational age [10]. The incidence of pre-term delivery increased by 46% in those complicated by surgery, compared to those not complicated by surgery [10]. This should be kept in mind.

The review is meant to alert obstetricians on the critical role of ultrasound in enhancing accurate diagnosis in the face of a complex clinical condition like acute abdomen in pregnancy.

The cases

Case 1

Mrs S.A., a 28-year-old G6P4⁺⁰ with three living children (one of whom was delivered with a cleft lip), presented with left lumbar region pain. She did not book index pregnancy for antenatal care. All her previous deliveries were at home and were not complicated. Her last menstrual period (LMP) was June 7, 2013; expected date of confinement (EDC), March 14, 2014; estimated gestational age (EGA), 33+6. The pain in her left lumbar region started gradually and became very severe 3 days prior to presentation. It was associated with intermittent vomiting and constipation. There were no associated urinary symptoms or associated bleeding per vagina or drainage of liquor. She noted her abdomen to be growing bigger compared to gestational age. A day prior to presentation, she was admitted at a primary health-care center and was told that she was in labor. Her pain continued to worsen, and she was referred to our hospital. On examination, she was found to be in painful distress, dehydrated, and mildly pale. Her pulse rate was 118 beats per minute (BPM); blood pressure, 100/70 mm Hg; respiratory rate, 24 breaths per minute; her chest was clear. The abdomen was gravidly enlarged with irregular contour. The uterus was felt to be separated from a large cystic and tender mass occupying the upper abdomen; bowel sounds were not heard on auscultation. The uterus was about 34 cm, with the fetus lying transverse, no palpable contractions, and the fetal heart rate was 144 bpm. Vaginal examination shows the vulva and vagina were normal and the cervix was 3 cm long and posterior. Initial diagnosis was intestinal obstruction in pregnancy. An emergency ultrasound (2D) was done, with the following findings: a viable fetal lying transverse; biparietal diameter (BPD), 90.2 mm; EGA, 36+1; femur length (FL), 68.8 mm; EGA, 35 weeks; abdominal circumference (AC), 28.9 mm; EGA, 33 weeks; estimated fetal weight. 2.41 kg (Figure 1). The liquor was reduced, the left kidney was grossly hydronephrotic, and the right kidney was grossly normal (Figures 2 and 3). An assessment of acute abdomen with a normal intrauterine pregnancy and a huge left cystic hydronephrotic kidney was made.

Figure 1:

BPD and FL assessment of fetal gestational age.

Figure 2:

The normal right kidney and the grossly hydronephrotic left kidney.

Figure 3:

The grossly hydronephrotic left kidney.

A urologist was invited and made the same diagnosis. A limited intravenous urogram (IVU) was ordered to determine the function of both kidneys. The IVU revealed a functioning right kidney and a non-functioning left kidney. The patient was counseled based on the findings, and she consented to an emergency exploratory laparotomy and cesarean section. She was placed on intravenous fluid and analgesia. Complete blood count, electrolyte urea, and creatinine were tested, and the results were all within normal limits. Three pints of blood were grouped and cross-matched.

Findings at surgery

Findings show a live male fetus lying transverse, weighing 2.6 kg; the liquor was clear but scanty, and the placenta was fundal. A huge cystic left kidney was attached to the transverse colon and the omentum (Figure 4), with multiple cysts (Figures 5 and 6). The postoperative period was smooth, and both mother and infant did well and were discharged after 7 days. She came for follow-up 7 days after discharge, and there was no problem. Histology revealed benign hypoplastic cystic kidney secondary to distal obstruction.

Figure 4:

The gross picture of the left cystic kidney attached to the omentum and the transverse colon and the gravid uterus protruding from below.

Figure 5:

The affected kidney with multiple cysts after removal.

Figure 6:

The affected kidney after removal with atrophic remaining kidney tissue.

Case 2

Mrs M.Z., a 21-year-old primigravida, presented with severe right-sided lower abdominal pain and two episodes of fainting. Her LMP was March 15, 2014; EDC, December 26, 2014; EGA, 7+4. The patient was yet to book for antenatal care. The pain was intermittent, with onset 2 days prior to presentation, and became more severe and continuous and with associated vomiting, fever, and dysuria. She had a pregnancy test, which confirmed that she was pregnant before presentation. She had no history of bleeding per vagina. On examination, she was found to be anxious, in painful distress, and dehydrated. She was not febrile, pale, or anicteric. Her pulse rate was 104 bpm; blood pressure, 120/70 mm Hg; respiratory rate, 20 breaths per minute; her chest was clear. Abdomen was full, with a tender cystic swelling in the right iliac fossa. Vaginal examination revealed clean vulva and vagina and closed cervix, 3 cm posterior. The left adnexa felt normal, but the right adnexa was tender, cystic, and enlarged. An initial assessment of unruptured ectopic pregnancy to rule out appendicular mass and adnexal torsion. An emergency ultrasound (2D) scan revealed an intact gestational sac with fetal echo; GSD, 2.94 cm; EGA, 7+2; a right multiseptate ovary measuring 10×9.2 cm (Figure 7). Assessment showed acute abdomen and a right twisted ovarian cyst in a primigravida with an intact pregnancy.

Figure 7:

A multiseptate cystic ovary (left) and a gravid uterus with fetal echo (right).

The patient was counseled on the condition and treatment, and she consented to an exploratory laparotomy. She was placed on intravenous fluids and analgesics. Samples were obtained for complete blood count, electrolytes, urea and creatinine, and grouping and cross-matching of two pints of blood.

Findings at surgery

The exploratory laparotomy showed a bulky uterus about 12 weeks in size, normal left tube and ovary, and an enlarged cystic right ovary with a smooth and intact smooth capsule, measuring 10×8×4 cm, twisted three times on its pedicle (Figures 8–10). Ovarian cystectomy was done. The patient had a remarkable postoperative recovery and was discharged after 6 days. Histology revealed a corpus luteum of pregnancy. Two weeks later, she came for follow-up with no complaints and was advised to book for antenatal care.

Figure 8:

A multiseptate ovary.

Figure 9:

Grossly normal looking tubes bilaterally and a grossly normal looking ovary on the right side of the picture.

Figure 10:

Gross specimen of the cyst after cystectomy.

Discussion

Acute abdomen is a dangerous clinical condition that requires prompt evaluation and treatment. This is more so when the patient is pregnant because more than one life are at stake. Delay in presentation by the patient or delay in proper assessment and management at the hospital will only worsen the prognosis and lead to other catastrophic complications. Acute abdomen in pregnancy can be seen in all trimesters: the first case presented in the third trimester, whereas the second case was seen in the second trimester. Usually, patients with acute abdomen in pregnancy do not present with symptoms specific to a particular disease entity, but present with vague symptoms that rarely help in making a correct diagnosis. Both our patients presented with non-specific symptoms. Diagnosis became even more difficult because of the physiological changes of pregnancy. The initial diagnoses in both patients were wrong. Ultrasound evaluations in both cases accurately identified the affected organs, which led to their respective diagnoses. Ultrasound is the first choice in diagnosing acute abdomen in pregnancy [9] and has proven its efficacy in making accurate diagnosis in both cases.

In the first case, limited IVU was used to assess renal function, which guided us in making the decision to remove the atrophic affected kidney together with the cyst. IVU is known to expose the fetus to radiation along with its consequences; however, a limited form of the procedure was used to reduce the risk to the fetus. Again, we were reassured in using IVU because according to the American College of Radiology, no single diagnostic radiograph procedure results in radiation exposure to a degree that would threaten the well-being of the developing pre-embryo, embryo, or fetus [13]. Laparotomy confirmed the renal pathology, which is consistent with the ultrasound finding; however, the clinical features, although non-specific, pointed to an intestinal pathology. In good hands, therefore, ultrasound can be used to make a reliable pre-operative diagnosis when clinical findings are non-specific. The only diagnostic modality superior to ultrasound is MRI, which can clearly delineate the ovarian origin as well as the nature of the mass [11, 12].

During the operation, a twisted right ovarian cyst was found in case 2, which was diagnosed as a right ovarian cyst by ultrasonography, again proving its reliability in pre-operative diagnosis. Ovarian torsion is known to be more common in the right than in the left ovary [14].

With such a huge cystic mass in the second patient, the only treatment option is exploratory laparotomy. The management option of adnexal torsion in pregnancy remains controversial [15]. Traditionally, abdominal complications during pregnancy have been treated by laparotomy [15], and we used this management approach in our second patient; however, currently, laparoscopy is considered the preferable surgical option until approximately the 16th week of gestation [16].

One of the major complications of laparotomy during pregnancy is pre-term labor; however, in our second patient, this complication was not seen and pregnancy continued. Some workers advocate prophylactic tocolytic therapy, while others argue that it has no benefit [17, 18]. Our second patient was not given any tocolytics and the pregnancy continued.

Conclusion

Acute abdomen in pregnancy is an important clinical entity with the potential to lead serious maternal and fetal catastrophe if not meticulously managed. Diagnosis is complicated because of the physiological changes associated with pregnancy and the non-specificity of the symptoms. Some diagnostic modalities are not possible because of their possible effect on the fetus. Ultrasound is an effective tool in making accurate diagnosis in pregnancy in experienced hands. It is a safe, relatively inexpensive, and versatile technique that is readily available. It is non-invasive, can provide numerous information on both the mother and the fetus, and should always be considered as the first choice in diagnosis.