Dr Hunt has disclosed no financial relationships relevant to this article. Dr Srinivas has disclosed he is a consultant for Novartis, Alexion Pharmaceuticals, Inc, Boeringer Ingelheim, and ACI Clinical. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.
Examination of a dizygotic-dichorionic twin girl in the newborn nursery reveals a perineal sulcus. She was born at 38 weeks and 2 days gestation via cesarean section without instrumentation to a 30-year-old mother whose pregnancy was uncomplicated except for a positive Group B Streptococcus culture at 36 weeks’ gestation. The mother received incomplete intrapartum antibiotic prophylaxis during labor. Delivery was complicated by failure to progress during the first stage of labor, necessitating cesarean section. Apgar scores were 8 and 9 at 1 and 5 minutes, respectively. The mother took prenatal vitamins and promethazine during pregnancy. She denied tobacco, alcohol, and illegal drug use during pregnancy. The delivery room course was benign, and no abnormalities were noted in the delivery room examination.
The newborn appears appropriate for gestational age, with a birthweight of 3.55 kg (60th percentile), length of 47 cm (13th percentile), and head circumference of 34 cm (54th percentile). Initial evaluation of the perineum reveals a thickened appearance to the median raphe (Fig. 1). More thorough examination of the perineum with the infant’s legs flexed on the abdomen reveals a wet mucosal sulcus extending the length of the perineum from the posterior vaginal fourchette to the anterior anal verge (Fig. 2). The anal mucosa, caliber, and tone are normal. The anal wink is intact. The anus is in the appropriate position, and the infant has had witnessed normal stooling. Vaginal and urethral openings are normal in appearance and location. The spine is normal, with no obvious sacral abnormalities. She demonstrates normal neurologic function, including a plantar response with bilateral upgoing toes (positive Babinski sign), plantar grasp, and stepping reflexes. No other anatomic abnormalities are evident.
The diagnosis is established based on the clinical examination. The pediatric surgery consultant agrees with the diagnosis and recommends no further intervention.
The patient has a perineal groove, a rare congenital abnormality of uncertain pathogenesis.
Perineal groove is a rarely described congenital anomaly that is generally defined as a wet sulcus extending from the posterior fourchette of the vagina to the anterior anus. The “wet” appearance is due to the sulcus typically being lined with a mucous membrane. The incidence of perineal grooves is unclear because this anomaly is likely underrecognized and reported. In this patient, the defect was only visible when the thighs were fully flexed onto the abdomen (the diaper changing position). The anomaly is predominantly found in females; one case of a perineal groove in a male has been reported. The underlying pathogenesis remains unclear, although several hypotheses about the embryologic origin of the anomaly have been proposed. Hypotheses include incomplete fusion of the perineal raphe, incomplete fusion of the median genital folds, a remnant of an open cloacal duct, or a defect in the uroanal septum.
Conservative management is generally preferred for perineal grooves. The anomaly usually self-resolves, with epithelialization by 1 year of age. Surgical intervention is rarely indicated unless performed for cosmetic purposes. Complications requiring surgery are rare and include skin infections and persistent mucus drainage. If surgical intervention is indicated, it is typically performed after 2 years of age to allow for potential self-resolution. Screening for associated anomalies is not warranted because a perineal groove typically is an isolated finding. Only three cases of coexisting congenital anomalies have been described: hypospadias with bifid scrotum, ectopic anus, and an unspecified urinary tract anomaly.
Recognizing this anomaly is important because perineal grooves can be confused with other diagnoses, such as irritant dermatitis, hemangiomas, infection, lichen sclerosis, and sexual abuse. Identification of a perineal groove as a mild congenital abnormality can avoid unnecessary procedures and interventions.
No surgical intervention was required for the patient. No complications of the perineal groove arose. At her 6-month health maintenance visit, the perineal groove had fully epithelialized. She is growing and developing normally.
Perineal groove is described as a wet sulcus lined with mucous membrane extending from the posterior fourchette to the anterior anus.
Perineal grooves are rarely described in literature but are likely more common in practice.
The underlying pathogenesis and embryologic origin of perineal grooves are poorly understood.
Perineal grooves generally self-resolve by 1 year of age.
Surgical intervention is rarely indicated but can be considered for rare complications (infections, mucus drainage) or for cosmetic purposes, usually after 2 years of age.
Recognition of this mild anomaly can eliminate unnecessary (and potentially invasive) testing and procedures.
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