**4.4 Diagnosis**

Perineal endometriosis can be diagnosed on the basis of clinical features. According to our retrospective study of the 36 cases of PEM, 26 were PEM with anal sphincter involvement (Zhu et al., 2009). The early diagnosis and treatment of PEM is important for the prevention of progressive involvement of surrounding tissue (especially the anal sphincter), thus decreasing the risk of postoperative fecal incontinence. A detailed medical history is of great significance for the diagnosis. Three typical characteristics of perineal endometriosis for women of reproductive ages should be considered when taking a history: (1) past perineal tearing of episiotomy during vaginal delivery; (2) a tender nodule or mass at the perineal lesion; and (3) progressive and cyclic perineal pain. If these 3 criteria were met, the predictive value of perineal endometriosis was 100% (Zhu et al., 2009).

All cases of PEM (including 31 cases of PEM with anal sphincter involvement) at PUMCH met the abovementioned criteria on history and physical examination. Preoperative endoanal ultrasonography is a reliable technique for visualizing perianal endometriosis and for diagnosing anal sphincter involvement. Preoperative endoanal ultrasonography enables the surgeon to determine the operative approach and to explain the possible complications of sphincteroplasty to the patient (Bacher et al., 1999; Toyonaga, 2006; Watanabe et al., 2003).

Serum CA125 levels are of great clinical importance in the diagnosis of pelvic endometriosis. In other types of EM, the serum level of CA125 is of little significance. However, pelvic examination and ultrasonography should be performed when serum CA125 levels are elevated in a patient with PEM to exclude pelvic endometriosis.

Fig. 3. Histopathology: an endometrial gland in the sphincteric muscular tissue (H & E, ×100)

The pathology result of the excised lesions (endometrial glands and stroma in hyperplastic connective tissues) confirmed the diagnosis.
