Kinking, knotting, entrapment and breakage are very unusual complications related to epidural catheters that may prevent normal functioning or even hamper its withdrawal. There is no data regarding the incidence of epidural catheter kinking. Typically, the number of kinks is one or two, but there is a reported case of an epidural catheter presenting around 6 kinks [1-5].  We present here a clinical case of a laboring patient whose epidural catheter was found kinked in the inner body, precisely inside the epidural space, just after its placement.

A 26-year-old, 79 kg, American Society of Anesthesiologists Physical Status grade 3 (ASA-3) woman was assessed by an anesthesiology resident after having asked for laboring analgesia in a delivery room. She was in her 35th week of her first pregnancy and had penicillin allergy and asthma. Continuous epidural analgesia was indicated.
Standard monitorization was applied (blood pressure 130/65 mmHg, cardiac frequency 76 beats per minute and oxygen saturation with pulse oximeter 98%). She was placed in the sitting position and the L4-L5 interspinous process was approached in the midline with an 18-gauge Tuohy needle after subcutaneous local anesthesia with lidocaine 2%. Loss of resistance to saline was felt at 6 cm from skin and a Vygon® epidural catheter (made of polyether block amide, with inner diameter 0.45 mm, outer diameter 0.85 mm, 20 gauge, 90 cm length and three lateral eyes at its distal end) from a Vygon® epidural set (epidural set code 5191.337) was threaded. Some resistance to introduction was felt at the beginning but it later ceased and the catheter could be introduced. The catheter was fixed at 10 cm at the skin, leaving 4 cm inside the epidural space. No paresthesia nor bleeding occurred.
Aspiration was negative, but epidural test dose with lidocaine 2%, 60 mg could not be administered, as a complete obstruction to infusion was felt. The visible parts of the epidural catheter and the catheter connector were examined for kinks, but none were found. The catheter was then removed, showing a kink at 3 cm from the distal end (Figure 1). It was flushed with saline showing no dysfunction after the kink was stretched. The technique was then attempted again in the same interspinous process and a new epidural catheter was placed with an uneventful technique. The patient had a good level of analgesia during labor, maintained adequate hemodynamic stability, gave birth and the epidural catheter was withdrawn without any incidents.

Accidental kinking of an epidural catheter is very unusual and has been reported both proximal and distal to the skin entry [1-5]. Technical properties of epidural catheters such as the material, design and diameter can influence its tendency to kink, and this can be easily assessed by bending the catheter with two fingers, as suggested by Beamer and French [6].

Regarding physical characteristics, an epidural catheter should be firm enough to pass through the Tuohy needle easily and advance a few centimeters into the epidural space, but at the same time, it should be flexible enough to avoid tissue puncture, with the risk of dural puncture or intravascular cannulation. Newer catheters used nowadays are made of materials with a good balance between firmness and flexibility. Wire-reinforcement can also make catheters more resistant to kinking. The length of advancement of a catheter into the epidural space increases the risk of catheter kinking and displacement. For this reason, some authors recommend the insertion of no more than 2 cm with single end-hole catheters, and 4 cm with multiple hole catheters, as we did [1].

In our case, during catheter threading through the Tuohy needle, some resistance to introduction was felt and disappeared after pushing against resistance, as was also noted in other cases where catheter kinks were reported [4].

Baran O reported a clinical case of an epidural catheter kink where flushing was not checked after catheter placement and three hours later epidural anesthesia was required during surgery but catheter dysfunction was noted and conversion to general anesthesia was required [4]. Whenever an epidural catheter is placed, flushing should be attempted before its complete fixation on the skin, because this could ensure a normal functioning, as we performed in our case.

If a complete obstruction of an epidural catheter is found, the visible parts should be examined searching for kinks or knots formation. If no alteration is found, one possible way of relieving an occlusion is withdrawing the catheter slightly, which we did not attempt in our case. If the obstruction persists, complete withdrawal and new catheter placement may be necessary [1-5].

Kinking of an epidural catheter is a rare complication that usually requires the removal and new catheter placement, especially whenever the kink is located distal to the skin entry. Flushing the epidural catheter should be routinely performed after its placement to dismiss any possible kink or knot formation.

The author declares not having any conflict of interest, and have received no funding for the work.

The patient gave written informed consent for the scientific publication of her medical record and images.