Management of zipper entrapment injuries

INTRODUCTION — This topic will discuss the management of zipper entrapment injuries. Removal of hair tourniquets and other constricting bands are discussed separately. (See "Hair tourniquet and other narrow constricting bands: Clinical manifestations, diagnosis, and treatment".)

EPIDEMIOLOGY — Zipper entrapment injuries occur infrequently and most commonly involve the penis. In one case series from a pediatric emergency department (ED), one zipper entrapment injury occurred per 4000 new ED attendees [1]. In this series of 30 boys between the ages of 2 and 12 years of age, 60 percent of the affected boys were wearing underwear at the time of the injury. Most of the injuries were self-inflicted (84 percent) and occurred as the zipper was being zipped up as opposed to down (92 percent). Rarely, zipper injuries can occur on other parts of the body, such as the eyelid [2,3]. Most published cases of zipper injuries involve children, although zipper injuries in adults are described [4-6].

ANATOMY — In most instances, the uncircumcised foreskin is entrapped in the zipper (figure 1) [7]. Occasionally, redundant tissue on the ventral side of the circumcised penis is involved.

A zipper is composed of interlocking dentitions that are aligned by a fastener consisting of an inner faceplate, outer faceplate, and median bar (picture 1) [7]. The fastener and cloth hold the zipped dentitions together. If either the cloth or fastener is disrupted, the zipped dentitions fall apart.

INDICATIONS — The clinician should attempt removal of entrapped penile or other tissue as soon as possible after the zipper injury. With time, swelling and edema of the entrapped tissue makes successful management more difficult.

Penile entrapment that involves the urethra, or unsuccessful attempts using the procedures described below, warrants prompt referral to or consultation with a urologist.

PREPARATION — The child and caregiver or adult patient should receive an explanation of the procedure. Reassurance and a gentle approach to the injury help to gain patient cooperation and facilitate successful management.

Pain control — Attention to analgesia and anesthesia is essential in the management of males with zipper injuries. For pediatric patients, involvement of a trained child life specialist is advised to provide nonpharmacologic interventions to decrease the pain and anxiety caused by the procedure. (See "Procedural sedation in children: Approach", section on 'Nonpharmacologic interventions'.)

Local anesthesia — Topical anesthesia with liposomal lidocaine (eg, LMX) or lidocaine-prilocaine cream (eg, EMLA) has been shown to provide effective anesthesia for pediatric urologic procedures [8,9]. They may also be effective for alleviation of zipper entrapment, although such use has not been studied. Liposomal lidocaine is preferable because it does not require occlusion and is effective after only 30 minutes of application. (See "Clinical use of topical anesthetics in children", section on 'Liposomal lidocaine' and "Clinical use of topical anesthetics in children", section on 'Lidocaine-prilocaine'.)

If immediate management is necessary, local infiltration with lidocaine can be used before attempting zipper removal or disengagement of the entrapped penile skin. (See "Subcutaneous infiltration of local anesthetics".)

Dorsal penile block — Dorsal penile nerve block, more invasive and with potential for greater morbidity, should be reserved for entrapments involving a significant amount of tissue or skin. Ultrasound guidance has been described and, when performed by a trained provider, may decrease complications and provide more reliable local anesthesia than the blind technique [10]. Dorsal penile nerve block is performed as follows (figure 2) [11]:

●Cleanse the base of the penis with povidone-iodine solution.

●Prepare a syringe with 1 to 5 cc of 1 percent lidocaine or 0.25 percent bupivacaine without epinephrine. The maximum dose of 1 percent lidocaine is 5 mg/kg (0.5 mL/kg); the maximum dose of 0.25 percent bupivacaine is 2 mg/kg (0.8 mL/kg) (table 1).

●Insert the needle at the junction of the base of the penis and the suprapubic skin at the 10 o'clock position to a depth of 3 to 5 mm. A "pop" is usually felt as the needle pierces Buck fascia.

●Aspirate to ensure that the needle is not in a blood vessel.

●Infiltrate the area with one-half of the anesthetic dose.

●Repeat this process at the 2 o'clock position.

●Full anesthetic effect occurs after five minutes.

Complications of dorsal penile nerve block are uncommon. The most frequent complication is bruising. Formation of a hematoma occurs occasionally. Compression or vasospasm of the arterial supply may occur with large volumes of anesthesia or if epinephrine is used.

Systemic analgesia or sedation — For patients requiring systemic pain control, intravenous opioids or intranasal fentanyl are reasonable options. Intranasal fentanyl in children avoids the need for intravenous line placement. (See "Pediatric procedural sedation: Pharmacologic agents", section on 'Fentanyl'.)

Sedation, with appropriate monitoring and personnel, may be warranted in uncooperative children. Local or regional anesthesia is typically sufficient for managing zipper injuries in adults, although sedation may be necessary for adults with cognitive impairment or excessive anxiety. (See "Procedural sedation in children: Approach" and "Procedural sedation in adults in the emergency department: General considerations, preparation, monitoring, and mitigating complications".)

Equipment — The following materials should be assembled:

●Antiseptic solution (eg, povidone-iodine, chlorhexidine)

●Topical anesthetic (eg, liposomal lidocaine [LMX])

●Syringe with small gauge needle (eg, 27 gauge) with 1 percent lidocaine or 0.25 percent bupivacaine if local anesthetic infiltration or dorsal penile block is anticipated

●Mineral oil

●Wire cutters, bone cutters, or a mini hacksaw

●Flathead screwdriver

TECHNIQUES — The management of zipper injuries is based upon observational studies, primarily case reports and series [1,2,7,12-17]. The technique for managing zipper injuries depends upon the site of entrapment within the zipper (zipper teeth alone or zipper with fastener). The techniques described below work for plastic and metal zippers and skin entrapment of the penis, foreskin, and other sites.

Zipper teeth entrapment — When the skin is trapped between the zipper teeth but not the fastener (picture 1), cut the cloth of the zipper using scissors, which will result in separation of the zipper teeth (figure 3) [12]. If the zipper teeth are tightly engaged, then apply needle holders to the fabric on each side of the zipper and pull apart [6]. Local anesthesia or sedation is not typically necessary for this procedure.

Zipper fastener and teeth entrapment — The tissue is more difficult to release in patients in whom the penis or other tissue is entrapped within the zipper fastener (picture 1). Sedation may be necessary to complete procedures to perform these techniques in anxious or younger children or in patients with a large amount of tissue entrapment; local anesthesia usually is adequate for older children and adults. (See 'Pain control' above.)

The following methods have been described. The clinician should attempt the least painful and traumatic technique first:

●Apply mineral oil to the affected tissue for 10 to 15 minutes followed by gentle traction to free it [13]. The mineral oil technique is simple, nonthreatening, and typically avoids the need for sedation and additional tissue trauma. Anecdotal experience suggests that mild liquid soap (eg, dishwashing liquid) may provide sufficient lubrication if mineral oil is not available. This technique has been demonstrated to have the highest success rate in a simulated model using chicken skin [18]. This technique is also suitable for entrapment of skin at other sites, such as the eyelid [3].

●If use of mineral oil and traction is unsuccessful, then next steps depend upon the site of entrapment:

•Eyelid – Because of the potential for damage to the eye from metal filings or unintentional trauma during disabling of the fastener, consultation with an ophthalmologist is warranted.

•Penis and/or foreskin – Options include:

-Cut the median bar of the fastener (picture 1) using wire cutters, bone cutters, or a mini hacksaw (picture 2 and figure 4) [1,14-16]. This approach permits the mechanism to fall apart and leads to release of the entrapped tissue. This technique may be more difficult with heavy duty metal zippers and success may depend on the strength of the operator and the availability of bone cutters. Edema of trapped tissue may also limit access to the median bar [19].

-Place the thin blade of a flathead screwdriver between the inner and outer faceplates on the side of the fastener in which the tissue is not entrapped (picture 3). The blade is then rotated toward the median bar to widen the gap between the faceplates and release the tissue [17].

-Using either needle holders or hemostats, grasp the upper end of the fastener with one hemostat and the lower end of the fastener with a second hemostat. Pull the hemostats in opposite directions to widen the gap between the faceplates [6].

-Using a ring cutter, cut across the top of the faceplate on the side of the fastener in which the tissue is not entrapped [4].

-After achieving local anesthesia, unzip the zipper back over the entrapped skin or apply lateral traction to the zipper teeth to pull the zipped portion of the zipper apart. Both of these techniques may increase the trauma by repeating the injury to the affected area.

If penile tissue remains trapped despite use of these techniques, then prompt consultation with a urologist is warranted for consideration of local excision of entrapped tissue or circumcision.

WOUND MANAGEMENT — The penile tissue is frequently swollen and bruised after a zipper injury. Superficial abrasions may also occur. The urethra should be carefully inspected for potential injury.

Patients with eyelid entrapment should warrant a complete eye examination including fluorescein staining to assess for an associated corneal abrasion.

Patients with skin breaks should receive tetanus prophylaxis as indicated (table 2).

AFTERCARE — The caregiver should be informed that pain with urination may occur for one to two days after a penile zipper injury. Dysuria can be moderated by applying triple antibiotic ointment to any skin wounds and by allowing the patient to void while sitting in a tub of warm water.

The caregiver should be advised to seek medical attention if the patient is unable to void or has hematuria or develops signs of infection.

Skin at other sites should also undergo local care as described above, and caregivers should be advised to monitor for signs of infection.

SUMMARY AND RECOMMENDATIONS

●With most zipper injuries, the uncircumcised foreskin is entrapped in the zipper. Entrapment of the eyelid has also been described. (See 'Anatomy' above.)

●A zipper is composed of interlocking dentitions that are aligned by a fastener consisting of an inner faceplate, outer faceplate, and median bar (picture 1). If the fastener or cloth of the zipper is disrupted, the edges will fall apart. (See 'Anatomy' above.)

●The clinician should attempt removal of entrapped tissue as soon as possible after the zipper injury. (See 'Indications' above.)

●Attention to analgesia and anesthesia is essential in the management of zipper injuries. In children, involvement of a trained child life specialist is advised to provide nonpharmacologic interventions to decrease the pain and anxiety caused by the procedure in addition to any pharmacologic interventions. In adults, local or regional anesthesia are typically adequate. (See 'Pain control' above.)

●When the tissue is entrapped between the zipper dentitions without involvement of the fastener (picture 1), then the clinician may free the tissue by cutting the cloth that holds the zipper (figure 3). (See 'Zipper teeth entrapment' above.)

●When the tissue is entrapped in the zipper and zipper fastener, then several possible methods may be used. The clinician should attempt the least painful and traumatic technique first, consisting of application of mineral oil (or, if mineral oil is not available, dishwashing soap) followed 10 to 15 minutes later by gentle traction. (See 'Zipper fastener and teeth entrapment' above.)

●If use of mineral oil and traction is unsuccessful, then next steps depend upon the site of entrapment (see 'Zipper fastener and teeth entrapment' above):

•Eyelid – Because of the potential for damage to the eye from metal filings or unintentional trauma during disabling of the fastener, consultation with an ophthalmologist is warranted.

•Penis and/or foreskin – Options include cutting of the median bar of the fastener (picture 2 and figure 4), cutting or splaying the faceplate on the side of the fastener where there is no entrapped skin (picture 3), or, after assurance of local anesthesia, unzipping back over the entrapped skin.

If penile tissue remains trapped despite use of these techniques, then prompt consultation with a urologist is warranted for consideration of local excision of entrapped tissue or circumcision. (See 'Techniques' above.)

●The penile tissue is frequently swollen and bruised after a zipper injury. Superficial abrasions may also occur. The urethra should be carefully inspected for potential injury.

After release of eyelid entrapment, the clinician should perform a complete eye examination including fluorescein staining to assess for corneal abrasions. (See 'Wound management' above.)

●Patients with skin breaks should receive tetanus prophylaxis as indicated (table 2).