ORIGINAL CONTRIBUTIONS Anal Sphincter Injury After Vaginal Delivery in Primiparous Females Carlos Belmonte-Montes, M.D., Gonzalo Hagerman, M.D., Paul Alan Vega-Yepez, M.D., Enrique Hern indez-de-Anda, M.D., Vicente Fonseca-Morales, M.D. From the Colorectal Clinic, Hospital Central Militar, Mexico Cily, Mexico PURPOSE: The purpose of this study was to determine the incidence of anal sphincter injury and fecal incontinence after vaginal delivery. METHODS: This was a prospective, descriptive, observational study conducted over a three- year period in healthy primiparous females with previously intact anal sphincter and normal continence and without history of anorectal surgery. All patients completed a con- tinence questionnaire and underwent endoanal ultrasound four to six weeks before and six weeks after delivery. RESULTS: Ninety-eight primiparous females had either in- strumental (vacuum or forceps) vaginal delivery (n = 23) or noninstrumental vaginal delivery (n = 75). Twenty patients, 11 (48 percent) after instrumental delivery and 9 (12 per- cent) after noninstrumental vaginal delivery, had clinical sphincter tears that required primary repair. Twenty-eight patients (29 percent), 19 with previously repaired sphincter injury, had ultrasonographic defects that involved the ex- ternal sphincter (n = 19) or both the internal and external sphincter (n = 9). Twenty-one patients (75 percent) with ultrasonographic sphincter defects had either major (n = 5) or minor (n = 16) fecal incontinence. CONCLUSION: Anal sphincter injuries, many of them undiagnosed at the time of delivery, are common in primiparous females after vaginal delivery, especially if vacuum or forceps are used. These injuries cause fecal incontinence in a significant proportion of the patients. Patients undergoing vaginal delivery should be aware of the risks of anal sphincter injury. [Key words: Fecal incontinence; Endoanal ultrasound; Delivery; Sphinc- ter injury; Sphincter disruption] Belmonte-Montes C, Hagerman G, Vega-Yepez PA, Hernfin- dez-de-Mlda E, Fonseca-Morales V. Anal sphincter injury after vaginal delivery in primiparous females. Dis Colon Rectum 2001;44:1244-1248. F ecal incontinence is a common medical problem that is personally and socially incapacitating. ~ It is well known that fecal incontinence is more frequent in fcwnales than in males, and the reason for this difference is considered to be childbirth. 2-5 Because the stigma of this condition is considerable, many patients hide their Read at the meeting of The American Societyof Colon and Rectal Surgeons, Boston, Massachusetts, June 24 to 29, 2000. No reprints are avaiIable. symptoms, and therefore, the true incidence of fecal incontinence remains unknown. 6-a3 Clinical trials have been undertaken to determine the cause of anal sphincter damage and symptoms of fecal incontinence after vaginal delivery. 4'r-~2 Anal sphincter lesions occur more often during the first delivery, 6 whereas pudendal neuropathy seems to be related to consecutive deliveries. 4 Obstetric tears of the sphincter complex are often repaired at the time of delivery. However, recent studies have reported that many of these patients have a suboptimal out- come and complain of various degrees of anal incon- tinence. 1a-~4 Repeated injuries of the anal sphincter occur with successive deliveries, which confuses analysis in populations of mixed parity. ~5'16 There- fore, we studied prospectively a group of healthy females delivering their first babies, in whom labor was managed according to a standardized, estab- lished protocol. The aim of the present study was to determine the incidence of anal sphincter injury and fecal incontinence after vaginal delivery in primipa- rous patients in Mexico. PATIENTS AND METHODS During the period between November 1996 and May 1999, we conducted a prospective, observa- tional, longitudinal study" in primiparous females recruited from the obstetrics outpatient clinic at the Medical Specialties Center of the Mexican Army and Air Force. Healthy females without histow of anal sphincter damage and with normal continence were included. Females with a past history of dia- betes mellitus or neurological disease (central or peripheral), with previous anorectal or vaginal sur- gery, or subject to cesarean section were excluded. 1244