Rare and Interesting Case of Urorectal Septum Malformation

INTRODUCTION

The urorectal septum malformation (URSM) sequence is a rare spectrum of malformations involving various organ systems. The URSM sequence was first described by Escobar et al.¹ in 1987. Various structures of the genitourinary system and the lower part of the gastrointestinal tract develop from the caudal end of the mesoderm. The defective caudal end of the mesoderm leads to a spectrum of malformations. The URSM sequence is a disorder of abnormal development of the caudal end of the mesoderm. The name is based on the hypothesis that the cause of these septum malformations is failure of the urorectal septum to fuse with the cloacal membrane. It is a rare malformation with an incidence of 1 in 35,000–250,000 neonates.

Wheeler and Weaver^2,3 defined partial URSM as a single perineal or anal opening draining a common cloaca along with an absent (imperforate) anus, which is sometimes called persistent cloaca in females. In contrast, absence of both perineal and anal opening is called the complete URSM sequence, which is highly lethal due to severe renal dysfunction and pulmonary hypoplasia.⁴ The cases not fulfilling strict diagnostic criteria of the URSM sequence but with varying combinations of lower genitourinary and anal anomalies are grouped under the partial URSM sequence or lower mesodermal defects. The complete URSM sequence is a lethal defect and leads to stillbirth or perinatal death.

URORECTAL SEPTUM–EMBRYOLOGICAL DEVELOPMENT

The hindgut follows the midgut, in the embryo, and extends from the posterior intestinal portal to the cloacal membrane. It gives rise to the left one-third or distal portion of the transverse colon, the descending colon, the sigmoid or pelvic colon, the rectum, the upper portion of the anal canal, and part of the urogenital system (e.g., the bladder and urethra). It is supplied by the inferior mesenteric artery.

The terminal part of the hindgut continues into the cloaca, which is an endoderm-lined cavity that is in direct contact with the surface ectoderm.

The cloacal membrane is composed of endoderm of the cloaca and ectoderm of the proctodeum or anal pit

The terminal part of the hindgut, the cloaca, receives the allantois ventrally and the mesonephric ducts laterally (Fig. 1).

During development, a coronal wedge or ridge of mesenchyme, the urorectal septum, forms in the angle between the allantois and the hindgut

• As the septum grows caudal toward the cloacal membrane, it divides the cloaca into an anterior portion, the primitive urogenital sinus, and a posterior part, the anorectal canal (Fig. 2A).
• By 7 weeks of age, the urorectal septum reaches the cloacal membrane and fuses with it. Thus, the membrane is divided into a posterior anal membrane and a larger anterior urogenital membrane. The area of fusion of the urorectal septum and the cloacal membrane becomes the perineal body (Fig. 2B).
• In week 9, proliferation of mesenchyme around the anal membrane raises the surrounding ectoderm to form a shallow pit, the anal pit or proctodeum. The surrounding swellings are called the anal folds. Soon after, the anal membrane, at the bottom of the anal pit, ruptures to establish the anal canal, an open pathway from the rectum to the outside (Fig. 2C).

CASE DESCRIPTION

A 25-year-old female patient had attended the clinic for seeking treatment for fertility as the patient had been married for 4 years having active married life of 1 year and was unable to conceive. Detailed history was taken regarding menstruation—which suggested that patient had regular cycles. There was no significant past, personal, medical, or surgical history.

On examination, patient was well built and well nourished. On per speculum examination, there was passage of flatus while performing the examination, which arouse suspicion of some anomaly and so we checked for number of perineal openings and to our surprise found that there was only single opening in the perineum. On local examination, there was a single opening that was mostly the anal canal with two dimple-like openings on the labia minora on both sides with a normal urethral opening (Fig. 3). The patient was subjected to further investigation in which transabdominal ultrasound was performed, which revealed normal kidneys, no demonstrable ureteric dilatation or stone, septum in bladder, and normal ovaries with bicornuate uterus (Fig. 4A).

We discussed need for further investigation with the patient and with informed consent performed diagnostic laparoscopy.

On laparoscopy, the findings were as follows (Fig. 5):

• Uterus–bicorporeal
• Ovaries–both normal
• Tubes–both normal
• A band was present extending from the bladder to the rectum passing between the two horns of the uterus.
• There was complete absence of large bowel and direct communication between the caecum and the rectum with abnormal anatomy.

We performed cystoscopy, which confirmed a partial septum in the bladder (Fig. 4B).

We dilated the two dimple-like vaginal openings and performed hysteroscopy, which reveal two cervix and two uterine cavities (Fig. 6).

Barium enema done, which revealed absent ascending, transverse, and descending colon.

Multiple detector computed tomography (MDCT) of the abdomen and the pelvis revealed following abnormalities (Fig. 7C):

• Uterus didelphys with duplicated endometrial-endocervical cavities and vagina
• Incomplete septated urinary bladder
• Short caecum with a normal ileocecal junction. The caecum opens into a pouch-like colonic segment, which further continues as the rectum-anal canal and lies in-between the two uterine cavities–possibly the congenital pouch colon.

Since the patient has been continent for all these years of life, she is not willing to undergo any further surgery. She was advised dilatation of the existing vaginal openings so as to maintain normal sexual life.

DISCUSSION

The URSM sequence is rare but lethal malformation leading to death of the fetus in utero or in neonatal period. Usually, URSMs are associated with anomalies in either the gastrointestinal and urinary tract, commonly, skeletal system, and sporadic associations with other systems.

Many theories postulated about the pathogenesis of URSMS. Escobar et al.¹ proposed deficient growth of URS as a cause of complete URSMS, and improper induction of the mesenchymal tissue in the presence of the intact cloacal membrane results in ambiguous genitalia (Escobar et al.). Wheeler hypothesized that partial development of the urorectal septum and incomplete breakdown of the cloacal membrane result in partial URSMS (Wheeler and Weaver).^2,3 He suggested that mechanical interference due to the persistence of the cloaca as a cause for developmental abnormality of internal genital organs.

The complete URSM sequence is lethal and life-threatening for the fetus. The partial URSM sequence, however, is associated with prolonged life expectancy but requires a multidisciplinary approach to correct genitourinary, gastrointestinal, and skeletal malformations.

Till date, lot of publications^5–13 have been published regarding the URSM sequence and almost all of these studies have been retrospective but none of them have reported a case living with such malformation without any intervention till adulthood and most of them succumb early in life due to complicated and extensive interventions necessary.

We have represented a case of partial URSM sequence surviving without any problem at an advanced age and has been diagnosed with the condition accidentally when seeking treatment for infertility. Since the patient is having no complains with her routine life, we have suggested no intervention except for dilatation of vaginal openings in order to preserve the quality of life and maintain her sexual life.

REFERENCES

1. Escobar LF, Weaver DD, Bixler DB, et al. Urorectal septum malformation sequence. Am J Dis Child 1987;141(9):1021–1024. DOI: 10.1001/archpedi.1987.04460090098038.

2. Wheeler PG, Weaver DD, Obleime MO, et al. Urorectal septum malformation sequence: report of thirteen additional cases and review of the literature. Am J Med Genet 1997;73(4):456–462. DOI: 10.1002/(SICI)1096-8628(19971231)73:4<456::AID-AJMG15>3.0.CO;2-Q.

3. Wheeler PG, Weaver DD. Partial urorectal septum malformation sequence: a report of 25 cases. Am J Med Genet 2001;103(2):99–105. DOI: 10.1002/ajmg.1510.

4. Williams IV DH, Fitchev P, Policarpio-Nicolas MLC, et al. Urorectal septum malformation sequence. Urology 2005;66(3):657. DOI: 10.1016/j.urology.2005.03.003.

5. Jo Mauch T, Albertine KH. Urorectal septum malformation sequence: insights into pathogenesis. Anat Rec 2002;268(4):405–410. DOI: 10.1002/ar.10180.

6. Chien JC, Chen SJ, Tiu CM, et al. Is urorectal septum malformation sequence a variant of the vertebral defects, anal atresia, tracheoesophageal fistula, renal defects and radial dysplasia association? report of a case and a review of the literature. Eur J Pediatr 2005;164(6):350–354. DOI: 10.1007/s00431-005-1630-2.

7. Lubusky M, Prochazka M, Dhaifalah I, et al. Concordant partial urorectal septum malformation sequence in monozygotic twins. Am J Med Genet A 2006;140(24):2828–2831. DOI: 10.1002/ajmg.a.31523.

8. Escobar LF, Heiman M, Zimmer D, et al. Urorectal septum malformation sequence: prenatal progression, clinical report, and embryology review. Am J Med Genet A 2007;143A(22):2722–2726. DOI: 10.1002/ajmg.a.31925.

9. Kanamori Y, Iwanaka T, Nakahara S, et al. Survival in a neonate with complete urorectal septum malformation sequence after fetal vesico-amniotic shunting for a prominently dilated cloaca. Fetal Diagn Ther 2008;24(4):458–461. DOI: 10.1159/000177038.

10. Jain D, Sharma MC, Kulkarni KK, et al. Urorectal septum malformation sequence: a report of seven cases. Cong Anom 2008;48(4):174–179. DOI: 10.1111/j.1741-4520.2008.00200.x.

11. Tennant PW, Glinianaia SV, Wellesley D, et al. Epidemiology of partial urorectal septum malformation sequence (or “persistent cloaca”): a population-based study in seven regions of England and wales, 1985–2010. Arch Dis Child Fetal Neonatal Ed 2014;99(5):F413–F418. DOI: 10.1136/archdischild-2014-306027.

12. Aggarwal S, Phadke SR. Recurrence of urorectal septum malformation sequence spectrum anomalies in siblings: time to explore the geneticS. Am J Med Genet A 2013;161A(7):1718–1721. DOI: 10.1002/ajmg.a.35950.

13. Shah K, Nayak SS, Shukla A, et al. Spectrum of urorectal septum malformation sequence. Congenital Anomalies 2016;56(3):119–126. DOI: 10.1111/cga.12149.