The Physics of LEEP

LEEP makes use of low voltage and relatively high frequency electric current. In cutting mode, the high frequency current is produced in a smooth, uninterrupted sine wave. As the loop is introduced to the tissue, an arc occurs near the point of contact, causing the cells to be rapidly heated and explode into steam. The steam envelope allows for continued arcing, thus extending the cut. This produces a clean cut with little coagulation artifact. The transformation zone can thus be removed, with a good specimen sent to pathology. In the coagulation mode, fulguration of tissue is produced with short bursts of high peak voltage current. This mode is often used with a ball electrode to achieve hemostasis. Most modern units can combine the amount of cutting and coagulation currents in blend modes. With all operational modes, the current is quickly dispersed to the grounding electrode. The large surface area of the return electrode prevents high charge density and thus prevents burns. An improperly applied return electrode can cause burns.

Efficacy and patient acceptance of LEEP compare favorably with other methods of cervical treatment. Studies indicate LEEP is 91 to 98 percent effective in treating SILs (Tables 1 and 2). 1, 5 - 12 This compares to 81 to 95 percent success rate for cryosurgery 13, 14, 15 and 83 to 94 percent for laser. 5 LEEP is also a well-tolerated procedure, with 85 percent of patients reporting no discomfort. Most patients who do report discomfort indicate the degree of pain is mild. 1, 5, 10 Pregnancy rates after LEEP are comparable to laser therapy and better than rates for conization. 3 There also appears to be no significant difference in complications during pregnancy between patients who undergo LEEP and those who have other destructive cervical therapies. 16, 17 

Table 1. Recurrence rates for single LEEP procedures from the English language literature.

Ref   # in    Recurrence  Time in    Follow-up
      Study   Rate        Follow-up  Test          
------------------------------------------------
1     616     3.4%        6 months   Pap
5     98      6.3%        6 months   Pap
6     1000    4.1%        4 months   Pap / Colpo
7     721     4.6%        3 months   Pap / Colpo
8     52      5.8%        6 months   Pap / Colpo
9     860     5.5%        2 years    Pap
10    324     9%          1.5 years  Pap
11    198     7.6%        1 year     Pap / Colpo
12    102     9%          3 months   Colpo

Table 2. Recurrence rates for second LEEP procedures after recurrence from the English language literature.

Ref   # in    Recurrence  Time in    Follow-up
      Study   Rate        Follow-up  Test          
------------------------------------------------
9     44      2%          < 2 years  Pap

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