Sterile water papules, or the injection of sterile water into the tissue just below the skin in the sacro-lumbar area, is an old method of pain relief in labor.  It was first mentioned as a technique to alleviate surgical pain by the noted surgeon William Steward Halsted in 1885. and seems to go in and out of fashion.  The technique is effective, easy to administer, requires minimal equipment (a syringe with needle and a vial of sterile water) and is without side effects.  It is particularly useful for the low back pain associated with posterior position of the fetus as he/she moves downward into the birth canal.  It can be done in any birth setting, so it is particularly useful in out-of-hospital settings where other methods such as epidural anesthesia are not   Disadvantages include the severe burning or stinging sensation which occurs as the water is injected and the relatively short action time, from one to two hours.  Why does it work?  One theory that makes sense is that the Gate Control Theory; the sudden burst of intense pain from the injection closes off the transmission of sensation from other stimuli, such as labor contractions.  The use of counter-pressure with the fist or heel of the hand of an assistant at the same points may work the same way, although not as effectlvely and only for as long as the pressure is being maintained.

In my experience, the injection of sterile water works quite well in most cases, but women are hesitant to have the procedure done again when the effect wears off, remembering the searing pain from the injections themselves.  It is certainly worth a try if nothing else is working to relieve back labor.

Martensson L, McSwiggin M, Mercer JS (2008).  US Midwives’ Knowledge and Use of Sterile Water Injections for Labor Pain. J Midwifery Womens Health. 2008;53(2):115-122.

Reynolds JL (1994). Intracutaneous Sterile Water for Back Pain in Labour.  Can Fam Physician. 1994 October; 40: 1785-8, 1791-2.