Double Knot Research Articles

Morphological studies of Dalkon Shield tails removed from patients

Examination of the tails of Dalkon Shields removed from patients showed that approximately 34% of the tails had breaks or holes in the nylon sheath immediately below the double knot at the base of the Shield. The location of these holes is such that most of them would have been within the endometrial cavity. For control purposes, unused sterile Shields were removed from their pouches, and the tails were inspected for breaks in the sheath. Breaks were found in approximately 9% of these. Most of the holes were in the same location as those seen in tails removed from patients. The internal contents of the short terminal segments of Dalkon tails located beyond the double knot, from Shields removed from patients, were studied. Thirty-five (35) segments were evaluated by phase contrast microscopy and 10 were studied subsequently by transmission electron microscopy. Bacteria were found within the interfilamental spaces inside the sheath of 8 of the 10 tails. These observations suggest that bacteria which have ascended through the tail from the vagina could exit through these breaks in the sheath or from the terminal end of the tail directly into the endometrial cavity. The potential clinical implications of the data presented in this paper must be taken into consideration in the management of the non-pregnant asymptomatic wearer of a Dalkon Shield.

The commutator group of a doubled knot

The commutator group of a doubled knot