Mesenteric cysts are rare abdominal tumors.¹ Since the first autopsy description by Benivieni in 1507,¹ approximately 1,000 cases have been reported in the literature.² Of these, only 5 were managed during pregnancy.^{3, –, 7} These cysts vary in size, being uni- or multilocular, and most often involve the small bowel mesentery.^5,8 The conventional treatment involves laparotomy and surgical excision,¹ but recently the laparoscopic approach has been described in the nonpregnant.^{2,8, –, 12}

To the best of the author' s knowledge, this is the first report of laparoscopic excision of a mesenteric cyst during pregnancy. The relevant literature is reviewed.

A 23-year-old Saudi woman, gravida 1, para 0, was admitted at 20-week' s gestation for the management of an abdominal mass. She was otherwise well with an uneventful antenatal course. Two weeks prior to admission, an asymptomatic 17.2 × 12 × 10.6-cm echo-free cystic mass in the left hypochondrial region was discovered during routine abdominal ultrasound examination at another hospital, where magnetic resonance imaging (MRI) confirmed the ultrasound finding. It also revealed crossed ectopia of the left kidney (Figure 1 and 2).

On abdominal examination, the uterus size was appropriate for a gestational age of 20 weeks, but the left hypochondrial mass was impalpable. Systemic examination was unremarkable. Laboratory tests were all within normal limits.

Repeat ultrasound examination in our hospital showed an intrauterine pregnancy with a single viable fetus, and the cyst was separate from the uterus, ovaries, spleen, and kidneys. The diagnosis of a mesenteric cyst was entertained.

An ultrasound-guided aspiration of the cyst yielded 1 L of clear fluid, and cytology showed no malignant cells. Postaspiration ultrasound the day after showed no change in the size of the cyst. Because of its large size, and fear of interference with the pregnancy, a decision was made, after consultation with the attending obstetrician, to excise the cyst. On September 16, 2001, the patient underwent a laparoscopic excision of the cyst while under general anesthesia with endotracheal intubation.

The incidence of mesenteric cysts is 1/102,500 to 1/250,000 hospital admissions.¹ In our hospital, only 1 case was operated on out of 317,677 admissions between 1981 and 2001. These cysts arise during embryologic development because of ectopic lymphatic tissue, obstruction of lymphatic vessels, or incomplete fusion of the leaves of the mesentery.¹¹

Mesenteric cysts are usually asymptomatic,^4,10 and approximately half are found incidentally.² The clinical presentation is related to the size and location of the cyst, with abdominal pain and distention being the most common symptoms.^1,4,10 Rarely, serious complications, such as torsion, infection, hemorrhage into the cyst, intestinal obstruction, obstructive uropathy, compression of the inferior vena cava, and malignant transformation, have been reported.^1,4,7,10

Modern imaging, including ultrasonography and MRI, can give a precise diagnosis of the cyst, as in our patient. MRI is superior to CT scan because of its multiplanar capabiility.¹² In our case, MRI also showed crossed ectopia of the left kidney. This finding may support the hypothesis that the mesenteric cyst was congenital in origin. To the best of the author's knowledge, a mesenteric cyst associated with crossed ectopia of the kidney has not been reported before.

Traditionally, the treatment of choice is laparotomy with complete excision of the cyst and segmental bowel resection, if necessary.¹ Although surgery should be avoided in pregnancy whenever possible, nonobstetric laparotomy is performed in 1.6% to 2.2% of pregnancies.¹³ In most of these, the outcome is satisfactory for both mother and fetus, particularly for planned procedures performed in the second trimester.¹⁴ The previously reported 5 cases of mesenteric cyst during pregnancy were successfully managed at laparotomy (Table 1).

Pregnancy used to be a contraindication to laparoscopic surgery, but recent literature has shown that laparoscopic intervention can be performed safely in the pregnant patient.^13,15 The well-documented advantages of laparoscopic surgery, viz, decreased postoperative pain, shorter hospitalization, good cosmesis, and rapid recovery, have been extended to include the pregnant patient. Furthermore, laparoscopic surgery may offer additional benefits to the pregnant woman as compared with the nonpregnant one. For example, rapid postoperative recovery should minimize the increased risk of thromboembolic disease associated with pregnancy.¹⁶ Also, less postoperative pain results in less medication exposure to the fetus.¹⁶ Minimal or no uterine manipulation during laparoscopic surgery should reduce the potential for preterm labor. Finally, less chance exists of incisional hernia, should the patient need surgery during the latter stages of pregnancy.¹⁶

Encouraged by others' experience with laparoscopic surgery during pregnancy,^13,15 the satisfactory outcome of laparoscopic excision of mesenteric cysts,^{2,8, –, 12} and, after gaining adequate experience in laparoscopic management of various abdominal conditions,^17,18 the author found it possible to manage the present case laparoscopically. Indeed, laparoscopic excision was a reasonable option in our patient because she was in the second trimester, with a well-circumscribed, noninfiltrating benign cyst seen on MRI.

The timing of laparoscopy in pregnancy is controversial. Although successful laparoscopic surgery has been reported for each trimester, the second trimester is the ideal time because organogenesis is complete, the risk of spontaneous abortion is low, the uterus size is not large enough to obscure the operative field, and the chance of uterine contraction is low relative to that in the third trimester.¹⁵

A major concern while performing laparoscopic surgery in pregnancy is to prevent injury to the uterus and the fetus. Opinion remains divided regarding the blind insertion of the Veress needle and the first trocar versus the open (Hasson) technique when performing laparoscopy during pregnancy.^19,20 Based on our experience with the closed technique particularly in patients with acute small bowel obstruction,¹⁷ we encountered no complications with this technique in the present case. We would, however, like to emphasize that our patient was not obese (body mass index=24kg/m2), had had no previous abdominal surgery, and the uterus was palpable just below the umbilicus. We feel that the open technique may be safer in other settings, such as in obese patients and those presenting in the third trimester.

Another concern about the laparoscopic technique is the physiologic and hemodynamic effect of CO₂ pneumoperitoneum on mother and fetus. Based on 1 animal study,²¹ CO₂ pneumoperitoneum induced a transient maternal hypercapnia and acidosis with similar fetal changes, as well as fetal tachycardia and hypertension. According to Glasgow et al,²² these changes were not observed in pregnant patients monitored during laparoscopic cholecystectomy.

In conclusion, what is believed to be the first successful laparoscopic excision of a mesenteric cyst during pregnancy is presented. The procedure offers pregnant patients the advantages of minimally invasive surgery and, with careful patient selection, may be the treatment of choice.